1. [CASE 1 — QUESTION 1]
A 20-year-old previously healthy man presents with a two-day history of polyuria, vomiting, and lethargy. He is tachypneic and clinically dehydrated. Laboratory values show glucose 540 mg/dL, arterial pH 7.18, bicarbonate 10 mEq/L, an elevated anion gap, and positive serum ketones, establishing a diagnosis of diabetic ketoacidosis (DKA) as the initial presentation of type 1 diabetes mellitus. After intravenous fluids and electrolyte assessment are underway, the team turns to insulin therapy. Which insulin and route are appropriate for the acute management of his ketoacidosis?
A) Subcutaneous insulin glargine as the primary agent to lower glucose acutely
B) Subcutaneous NPH (neutral protamine Hagedorn) insulin every 2 hours
C) An intravenous infusion of regular insulin, because regular insulin is the only preparation suitable for intravenous use and provides the titratable, rapid control required in diabetic ketoacidosis
D) Subcutaneous insulin degludec to provide a stable basal level during the acute illness
E) An intravenous infusion of insulin lispro, titrated to glucose
ANSWER: C
Rationale:
Diabetic ketoacidosis (DKA) is managed with an intravenous insulin infusion, and regular insulin is the only preparation suitable for intravenous use; it allows the rapid, titratable control needed to close the anion gap and correct hyperglycemia while fluids and electrolytes are managed.
Option A: Option A is incorrect because glargine is an acidic-formulation basal analog designed for subcutaneous depot action and is not used intravenously or for acute DKA glucose lowering.
Option B: Option B is incorrect because NPH is an intermediate-acting subcutaneous suspension, unsuitable for the titratable intravenous control DKA requires.
Option D: Option D is incorrect because degludec is an ultra-long-acting subcutaneous basal analog and cannot provide acute, adjustable control.
Option E: Option E is incorrect because, although lispro is rapid-acting, the standard and labeled intravenous insulin for DKA is regular insulin; analogs are not the preparation used for intravenous infusion in this setting.
2. [CASE 1 — QUESTION 2]
Continuing with the same patient. After several hours of intravenous regular insulin and fluids, his anion gap has closed, he is tolerating oral intake, and the team plans to transition him from the intravenous infusion to a subcutaneous basal-bolus regimen. Which transition strategy is most appropriate?
A) Administer the first dose of subcutaneous basal insulin 1 to 2 hours before discontinuing the intravenous infusion, so that subcutaneous insulin is active before the short-lived intravenous effect disappears, preventing rebound hyperglycemia and recurrent ketosis
B) Stop the intravenous infusion and give the first subcutaneous dose only once glucose rises above 250 mg/dL again
C) Discontinue the intravenous insulin abruptly and wait until the next scheduled meal to begin subcutaneous insulin
D) Overlap the infusion with a subcutaneous rapid-acting analog alone, omitting basal insulin entirely
E) Continue the intravenous infusion indefinitely because subcutaneous insulin cannot maintain control after DKA
ANSWER: A
Rationale:
Intravenous regular insulin has a very short circulating half-life, so when the infusion is stopped its effect dissipates within minutes; to avoid a gap that would allow rebound hyperglycemia and recurrent ketosis, the first subcutaneous basal dose should be given 1 to 2 hours before the infusion is discontinued so that subcutaneous insulin is already active during the changeover.
Option B: Option B is incorrect because waiting for glucose to rise above 250 mg/dL means the gap has already produced loss of control.
Option C: Option C is incorrect because an abrupt stop with a delay until the next meal leaves the patient without active insulin and risks recurrent ketosis.
Option D: Option D is incorrect because omitting basal insulin leaves hepatic glucose output unopposed and is inadequate after DKA.
Option E: Option E is incorrect because subcutaneous basal-bolus therapy is the appropriate maintenance regimen once the gap has closed and the patient is eating.
3. [CASE 1 — QUESTION 3]
Continuing with the same patient. He weighs 70 kg and is being initiated on a subcutaneous basal-bolus regimen. Using standard weight-based estimation for an insulin-naive patient with type 1 diabetes mellitus, which starting total daily dose (TDD) and basal-bolus division is most appropriate?
A) A total daily dose of about 7 units (0.1 unit/kg), given entirely as basal insulin
B) A total daily dose of about 140 units (2 units/kg), divided 50 percent basal and 50 percent bolus
C) A total daily dose of about 35 units (0.5 unit/kg), given entirely as a single mealtime bolus
D) A total daily dose of about 35 units (0.5 unit/kg), divided roughly 50 percent basal and 50 percent bolus with the bolus distributed across meals
E) A total daily dose of about 70 units (1 unit/kg), given entirely as basal insulin with no bolus
ANSWER: D
Rationale:
For an insulin-naive patient with type 1 diabetes mellitus, the starting total daily dose (TDD) is estimated at roughly 0.4 to 0.5 unit/kg per day, which is about 35 units for a 70 kg patient, divided approximately 50 percent basal and 50 percent bolus with the bolus distributed across meals.
Option A: Option A is incorrect because 0.1 unit/kg is a basal-only initiation dose used in type 2 diabetes, not full replacement in type 1, and it omits bolus coverage.
Option B: Option B is incorrect because 2 units/kg far exceeds a starting estimate and would risk severe hypoglycemia.
Option C: Option C is incorrect because a single mealtime bolus omits the required basal component.
Option E: Option E is incorrect because 1 unit/kg as basal only is both too high for initiation and lacks mealtime coverage.
4. [CASE 1 — QUESTION 4]
Continuing with the same patient. The team is choosing the basal insulin component for his regimen and is deciding between NPH (neutral protamine Hagedorn) insulin and a long-acting basal analog such as glargine or degludec. Which statement best supports selecting the basal analog?
A) NPH provides a flatter, more peakless profile than basal analogs, making it the safer basal choice
B) A long-acting basal analog provides a flatter, near-peakless profile compared with NPH, reducing the pronounced 4-to-8-hour peak that makes NPH a recognized cause of nocturnal hypoglycemia
C) The basal analogs are suitable for intravenous use, which NPH cannot match
D) NPH lasts longer than degludec, providing more stable 42-hour coverage
E) Basal analogs require twice-daily dosing in all patients, whereas NPH is always once daily
ANSWER: B
Rationale:
Long-acting basal analogs such as glargine and degludec provide a flatter, near-peakless pharmacodynamic profile, whereas NPH (neutral protamine Hagedorn) has a pronounced peak at roughly 4 to 8 hours that makes it a recognized cause of nocturnal hypoglycemia; the smoother analog profile is the basis for preferring it as the basal component.
Option A: Option A is incorrect because it inverts the profiles: NPH peaks, while the analogs are peakless.
Option C: Option C is incorrect because neither basal analogs nor NPH are used intravenously; only regular insulin is.
Option D: Option D is incorrect because degludec, not NPH, provides the longer (greater than 42-hour) duration, and NPH lasts only 12 to 18 hours.
Option E: Option E is incorrect because basal analogs are typically once daily (degludec flexibly so), and NPH is often given twice daily, so the claim is reversed.
5. [CASE 2 — QUESTION 1]
A 34-year-old woman with long-standing type 1 diabetes mellitus on twice-daily NPH (neutral protamine Hagedorn) insulin plus mealtime rapid-acting insulin reports recurrent hypoglycemia around 3 in the morning, with documented glucose readings in the 40s mg/dL, despite acceptable daytime control. Her bedtime NPH dose is given at about 10 in the evening. Which property of her basal insulin best explains the timing of these nocturnal episodes?
A) NPH is peakless, so the nocturnal hypoglycemia cannot be attributed to its time-action profile
B) NPH has a pronounced peak at roughly 4 to 8 hours after injection, so a 10 in the evening dose peaks in the early morning hours, accounting for the 3 in the morning hypoglycemia
C) NPH is a rapid-acting analog peaking within 1 to 2 hours, so its peak occurs near bedtime rather than early morning
D) NPH binds albumin and buffers its action, so it cannot cause hypoglycemia
E) NPH precipitates at neutral pH to form a 24-hour peakless depot, so its effect is constant overnight
ANSWER: B
Rationale:
NPH (neutral protamine Hagedorn) has a pronounced peak at roughly 4 to 8 hours after injection; a dose given at about 10 in the evening therefore peaks in the early morning, which explains the 3 in the morning hypoglycemia.
Option A: Option A is incorrect because NPH does have a distinct peak, which is exactly what drives nocturnal hypoglycemia.
Option C: Option C is incorrect because NPH is intermediate-acting, not a rapid-acting analog peaking at 1 to 2 hours.
Option D: Option D is incorrect because albumin binding describes detemir, and no insulin is incapable of causing hypoglycemia.
Option E: Option E is incorrect because pH-dependent peakless precipitation describes glargine, not NPH.
6. [CASE 2 — QUESTION 2]
Continuing with the same patient. To address the early-morning hypoglycemia driven by her basal insulin, the team decides to change the basal component. Which change most directly removes the mechanism responsible for her nocturnal episodes?
A) Increase the bedtime NPH dose to sustain higher overnight glucose
B) Move both NPH doses to the morning and rely on rapid-acting insulin overnight
C) Add a bedtime snack and make no change to the insulin regimen
D) Switch from rapid-acting mealtime insulin to regular insulin at meals
E) Replace the NPH with a peakless long-acting basal analog such as glargine or degludec, eliminating the early-morning peak that causes the nocturnal hypoglycemia
ANSWER: E
Rationale:
The nocturnal hypoglycemia results from the NPH (neutral protamine Hagedorn) peak landing in the early morning; replacing NPH with a peakless long-acting basal analog such as glargine or degludec provides flat basal coverage and removes the offending peak, directly addressing the mechanism.
Option A: Option A is incorrect because increasing the NPH dose intensifies the early-morning peak and worsens the hypoglycemia.
Option B: Option B is incorrect because shifting NPH to the morning and leaning on overnight rapid-acting insulin does not provide stable basal coverage and risks further hypoglycemia.
Option C: Option C is incorrect because a bedtime snack is a workaround that does not remove the peak and promotes weight gain.
Option D: Option D is incorrect because changing the mealtime insulin does not address the basal peak responsible for the nocturnal episodes.
7. [CASE 2 — QUESTION 3]
Continuing with the same patient. After switching to a peakless basal analog, her nocturnal hypoglycemia resolves, but she now has reproducible pre-breakfast hyperglycemia with normal values at bedtime and in the middle of the night. Which mechanism best explains this new fasting pattern?
A) Rebound hyperglycemia following an unrecognized nocturnal hypoglycemic episode caused by the new basal analog
B) Excessive basal analog dosing causing paradoxical morning hyperglycemia
C) The dawn phenomenon, an early-morning rise in cortisol and growth hormone that increases hepatic glucose production and insulin resistance between roughly 3 and 8 in the morning, producing pre-breakfast hyperglycemia
D) Delayed gastric emptying shifting her dinner absorption into the morning
E) Meter inaccuracy in the morning that does not reflect true glucose
ANSWER: C
Rationale:
The dawn phenomenon is an early-morning surge in counter-regulatory hormones, principally cortisol and growth hormone, that increases hepatic glucose production and insulin resistance between roughly 3 and 8 in the morning, producing pre-breakfast hyperglycemia; her normal middle-of-the-night values argue against a hypoglycemia-driven rebound.
Option A: Option A is incorrect because her documented normal nocturnal glucose excludes an unrecognized hypoglycemic rebound.
Option B: Option B is incorrect because excess basal insulin would tend to cause hypoglycemia rather than isolated morning hyperglycemia.
Option D: Option D is incorrect because delayed gastric emptying would not reliably produce an early-morning hepatic glucose rise with normal overnight values.
Option E: Option E is incorrect because the pattern is reproducible and physiologic, not a meter artifact.
8. [CASE 2 — QUESTION 4]
Continuing with the same patient. Her pre-breakfast hyperglycemia from the dawn phenomenon persists despite optimization of her once-daily basal analog. Which intervention most specifically targets the early-morning rise in hepatic glucose production?
A) Continuous subcutaneous insulin infusion (CSII, an insulin pump) programmed to deliver an increased basal rate between roughly 3 and 8 in the morning, an adjustment that matches the dawn-phenomenon interval and is not achievable with a single once-daily basal injection
B) A larger single morning dose of basal analog to blanket the entire 24-hour period
C) Switching the basal analog to NPH (neutral protamine Hagedorn) given at dinner
D) Eliminating the basal insulin and increasing only the breakfast bolus
E) Adding a bedtime rapid-acting insulin dose to lower the pre-dawn glucose
ANSWER: A
Rationale:
Continuous subcutaneous insulin infusion (CSII) allows programming of multiple basal rates across the day, including an increased rate during the dawn interval between roughly 3 and 8 in the morning; this precisely targets the early-morning rise in hepatic glucose production and cannot be reproduced by a single once-daily basal injection.
Option B: Option B is incorrect because a larger uniform morning basal dose raises insulin across the whole day and risks daytime and nocturnal hypoglycemia without specifically covering the dawn interval.
Option C: Option C is incorrect because reintroducing NPH brings back a peak that previously caused nocturnal hypoglycemia and does not cleanly target the dawn window.
Option D: Option D is incorrect because eliminating basal insulin is unsafe in type 1 diabetes and leaves overnight hepatic output unopposed.
Option E: Option E is incorrect because a bedtime rapid-acting dose acts too early and risks nocturnal hypoglycemia rather than covering the 3-to-8 in the morning rise.
9. [CASE 3 — QUESTION 1]
A 58-year-old man with type 2 diabetes mellitus and obesity has been intensified to a high-dose basal-bolus insulin regimen. Over six months he has gained 6 kg, his insulin requirements keep climbing, and his glycemic control is deteriorating in what appears to be a self-reinforcing cycle. He has established atherosclerotic cardiovascular disease. Which addition best attenuates further weight gain while maintaining glycemic control?
A) A sulfonylurea, which promotes weight loss when combined with insulin
B) A higher insulin dose, since additional insulin will independently reverse the weight gain
C) A thiazolidinedione, which reliably reduces weight in insulin-treated patients
D) A GLP-1 (glucagon-like peptide-1) receptor agonist or an SGLT-2 (sodium-glucose cotransporter-2) inhibitor, both of which attenuate insulin-associated weight gain while maintaining glycemic control and carry cardiovascular outcome benefit in type 2 diabetes
E) Switching all insulin to a premixed formulation, which prevents insulin-associated weight gain
ANSWER: D
Rationale:
Insulin intensification drives weight gain, which worsens insulin resistance and escalates requirements in a self-reinforcing cycle. Adding a GLP-1 (glucagon-like peptide-1) receptor agonist or an SGLT-2 (sodium-glucose cotransporter-2) inhibitor attenuates insulin-associated weight gain while maintaining glycemic control, and both classes have cardiovascular outcome benefit that is particularly relevant given his established cardiovascular disease.
Option A: Option A is incorrect because sulfonylureas tend to cause weight gain and hypoglycemia, not weight loss.
Option B: Option B is incorrect because more insulin promotes further weight gain rather than reversing it.
Option C: Option C is incorrect because thiazolidinediones are associated with weight gain and fluid retention.
Option E: Option E is incorrect because switching to a premixed insulin does not prevent the class effect of insulin-associated weight gain.
10. [CASE 3 — QUESTION 2]
Continuing with the same patient. Despite adjunctive therapy, his insulin requirement rises above 250 units per day, and the large injection volumes are producing erratic absorption and unpredictable glucose swings. Which insulin change best addresses the large-volume absorption problem?
A) Switch to U-500 regular insulin, which at 500 units/mL is five-fold concentrated, reducing injection volume by about 80 percent and improving absorption consistency in patients requiring very large doses
B) Continue U-100 insulin and divide each dose into numerous small injections at a single site
C) Switch to a U-100 rapid-acting analog given once daily
D) Reduce his insulin to 0.1 unit/kg and accept higher glucose to limit volume
E) Add a second U-100 basal analog to deliver the same total volume in two products
ANSWER: A
Rationale:
Subcutaneous absorption becomes erratic when injected volume exceeds roughly 50 units per site, which is the problem for a patient requiring more than 250 units per day. U-500 regular insulin is five-fold concentrated at 500 units/mL, reducing injection volume by about 80 percent and improving absorption consistency, with depot pharmacokinetics that allow twice- or three-times-daily dosing.
Option B: Option B is incorrect because many small injections at one site promote lipohypertrophy and do not solve the total-volume problem.
Option C: Option C is incorrect because a once-daily rapid-acting analog provides neither basal coverage nor adequate dosing for this requirement.
Option D: Option D is incorrect because deliberately undertreating to limit volume sacrifices glycemic control.
Option E: Option E is incorrect because splitting the dose across two U-100 products does not reduce the per-injection volume problem.
11. [CASE 3 — QUESTION 3]
Continuing with the same patient. Reviewing his medication history, the team notes that his deterioration accelerated after he was started on olanzapine for a psychiatric indication several months earlier. Which statement best explains the contribution of this medication?
A) Olanzapine improves insulin sensitivity, so it cannot be contributing to his rising requirements
B) Olanzapine accelerates renal insulin clearance, which is why more insulin is needed
C) Olanzapine, an atypical antipsychotic, promotes weight gain and insulin resistance, predictably increasing insulin requirements, so the team should coordinate with psychiatry about the antipsychotic choice while intensifying monitoring
D) Olanzapine is metabolically neutral, so the weight gain is entirely attributable to insulin
E) Olanzapine directly destroys pancreatic beta cells in the same way as a calcineurin inhibitor
ANSWER: C
Rationale:
Atypical antipsychotics such as olanzapine (and clozapine) promote weight gain and insulin resistance, predictably increasing insulin requirements; recognizing this prompts coordination with psychiatry about the choice of agent along with intensified glucose monitoring and anticipatory insulin adjustment.
Option A: Option A is incorrect because olanzapine worsens, not improves, insulin sensitivity.
Option B: Option B is incorrect because the effect is increased insulin resistance and weight gain, not accelerated renal clearance.
Option D: Option D is incorrect because olanzapine is not metabolically neutral; it is a major contributor to the weight gain.
Option E: Option E is incorrect because olanzapine acts chiefly through weight gain and insulin resistance rather than the direct beta-cell toxicity characteristic of calcineurin inhibitors such as tacrolimus.
12. [CASE 3 — QUESTION 4]
Continuing with the same patient. After his regimen is rationalized, his total daily dose (TDD) stabilizes at 90 units. The team wants to set a correction factor (CF, the expected glucose drop per unit of rapid-acting insulin) using the 1800 Rule. What is his approximate correction factor?
A) Approximately 90 mg/dL per unit, because the correction factor equals the total daily dose
B) Approximately 20 mg/dL per unit, because 1800 divided by the TDD of 90 equals 20, giving the estimated glucose drop per unit
C) Approximately 5 mg/dL per unit, because 500 divided by the TDD gives the correction factor
D) Approximately 1800 mg/dL per unit, because the rule sets the correction factor equal to the constant 1800
E) Approximately 50 mg/dL per unit, because the correction factor is fixed regardless of total daily dose
ANSWER: B
Rationale:
The 1800 Rule estimates the correction factor (CF) as 1800 divided by the total daily dose (TDD): 1800 divided by 90 equals 20, so 1 unit of rapid-acting insulin is expected to lower glucose by approximately 20 mg/dL. This is a starting estimate requiring individual titration.
Option A: Option A is incorrect because the CF is 1800 divided by the TDD, not equal to the TDD.
Option C: Option C is incorrect because the 500 constant is used to estimate the carbohydrate-to-insulin ratio (CIR), not the correction factor.
Option D: Option D is incorrect because the rule divides 1800 by the TDD rather than setting the CF equal to 1800.
Option E: Option E is incorrect because the correction factor depends on the TDD and is not a fixed value.
REFERENCE BOX
500 Rule: carbohydrate-to-insulin ratio (CIR, grams of carbohydrate covered per unit) is approximately 500 divided by the total daily dose (TDD).
1800 Rule: correction factor (CF, mg/dL lowered per unit of rapid-acting insulin) is approximately 1800 divided by the TDD.
Mealtime bolus = (grams of carbohydrate / CIR) + ((current glucose minus target glucose) / CF). These are starting estimates requiring individualized titration.
13. [CASE 4 — QUESTION 1]
A 64-year-old woman with type 2 diabetes mellitus on a basal-bolus regimen (insulin glargine each evening plus mealtime insulin aspart) is scheduled for elective hip replacement and will be NPO (nil per os) from midnight. The surgical and anesthesia teams ask how to manage her insulin on the morning of surgery. Which approach is most appropriate?
A) Give her full usual mealtime aspart doses on schedule despite being NPO to prevent hyperglycemia
B) Hold all insulin, including basal, the night before and morning of surgery
C) Double her basal glargine the morning of surgery to cover surgical stress
D) Replace her basal insulin with sliding-scale aspart alone as the sole regimen
E) Hold the rapid-acting aspart while she is NPO and continue her long-acting basal glargine at about 75 to 80 percent of the usual dose
ANSWER: E
Rationale:
Standard perioperative management holds all rapid-acting bolus insulin while the patient is NPO (nil per os) and continues long-acting basal insulin at roughly 75 to 80 percent of the usual dose, preventing both unopposed hepatic glucose output and fasting hypoglycemia.
Option A: Option A is incorrect because giving full mealtime insulin to a fasting patient invites hypoglycemia.
Option B: Option B is incorrect because withholding basal entirely risks hyperglycemia and ketosis.
Option C: Option C is incorrect because doubling basal insulin risks hypoglycemia and is not standard stress management.
Option D: Option D is incorrect because correction-scale insulin alone is an appropriate supplement to basal insulin but not a substitute for it.
14. [CASE 4 — QUESTION 2]
Continuing with the same patient. Intraoperatively and in the immediate postoperative period, the team sets a glucose goal. Which blood glucose target is most appropriate for this surgical patient?
A) 80 to 110 mg/dL, aiming for tight normoglycemia
B) Below 70 mg/dL to maximally suppress hyperglycemic complications
C) 200 to 250 mg/dL to avoid any risk of hypoglycemia
D) 140 to 180 mg/dL, balancing the risks of hyperglycemia against hypoglycemia, which is especially dangerous in the anesthetized patient who cannot report symptoms
E) No target is needed because glucose does not affect surgical outcomes
ANSWER: D
Rationale:
The recommended perioperative glucose target is 140 to 180 mg/dL, which balances the risks of hyperglycemia (impaired wound healing, infection) against those of hypoglycemia, which is particularly dangerous in an anesthetized patient who cannot report or respond to symptoms.
Option A: Option A is incorrect because an 80 to 110 mg/dL target is too tight and increases hypoglycemia risk.
Option B: Option B is incorrect because a target below 70 mg/dL is frankly hypoglycemic and unsafe.
Option C: Option C is incorrect because 200 to 250 mg/dL is excessively permissive and promotes hyperglycemic complications.
Option E: Option E is incorrect because perioperative glycemic control does affect outcomes such as infection and wound healing, so a target is needed.
15. [CASE 4 — QUESTION 3]
Continuing with the same patient. Her procedure becomes complicated and she is expected to remain NPO (nil per os) and critically ill for an extended period in the intensive care unit. Which method of insulin delivery now provides the most precise glycemic control?
A) An intravenous regular insulin infusion titrated by a structured algorithm with glucose monitoring every 1 to 2 hours, which provides the most precise control during prolonged critical illness and NPO status
B) Continuing only her usual subcutaneous basal glargine without monitoring
C) Switching to a once-daily premixed insulin for convenience
D) Oral hypoglycemic agents administered through a feeding tube
E) Subcutaneous degludec every 72 hours to minimize injections
ANSWER: A
Rationale:
For major surgery or critical illness with anticipated prolonged NPO (nil per os) status, an intravenous regular insulin infusion titrated by a structured algorithm with frequent glucose monitoring (every 1 to 2 hours) provides the most precise glycemic control.
Option B: Option B is incorrect because subcutaneous basal alone without monitoring cannot provide the responsive control a critically ill patient requires.
Option C: Option C is incorrect because a premixed insulin offers neither the titratability nor the precision needed here.
Option D: Option D is incorrect because oral agents are inappropriate in a critically ill, NPO patient and cannot be precisely titrated.
Option E: Option E is incorrect because an ultra-long-acting subcutaneous analog cannot be adjusted rapidly enough for a dynamically ill patient.
16. [CASE 4 — QUESTION 4]
Continuing with the same patient. A trainee asks why the intensive care unit infusion uses regular insulin rather than one of the rapid-acting analogs she takes at home. What is the best explanation?
A) Rapid-acting analogs are too slow in onset for intravenous use
B) Regular insulin is less expensive, which is the only reason it is chosen
C) Regular insulin is the only preparation suitable for intravenous use; analogs, NPH, and premixed formulations are not given intravenously because of altered pharmacokinetics and, for suspensions, particulate matter
D) Rapid-acting analogs cannot be diluted in saline for any route
E) Regular insulin uniquely binds the insulin receptor, which the analogs cannot do intravenously
ANSWER: C
Rationale:
Regular insulin is the only preparation suitable for intravenous use; the analogs, NPH (neutral protamine Hagedorn), and premixed formulations are not given intravenously because of altered pharmacokinetics and, for the protamine-containing suspensions, particulate matter. Regular insulin is the established and labeled choice for intravenous infusion.
Option A: Option A is incorrect because the issue is established suitability and labeling for intravenous use, not that analogs are too slow.
Option B: Option B is incorrect because the choice rests on suitability for intravenous administration, not merely cost.
Option D: Option D is incorrect because the relevant point is that regular insulin is the standard intravenous preparation, not a blanket claim that analogs cannot be diluted.
Option E: Option E is incorrect because all insulins act through the same insulin receptor; receptor binding is not the reason regular insulin is used intravenously.
17. [CASE 5 — QUESTION 1]
A 71-year-old man with type 2 diabetes mellitus and chronic kidney disease has had a falling estimated glomerular filtration rate (eGFR), now 25 mL/min/1.73m2. On his previously stable insulin regimen he has begun having more frequent hypoglycemia. Which mechanism best explains the increased hypoglycemia risk, and what is the appropriate response?
A) Declining renal function increases insulin clearance, so his dose should be increased
B) Declining renal function reduces insulin clearance because the kidney normally degrades a substantial fraction of peripheral insulin; insulin action is prolonged, raising hypoglycemia risk, so his insulin dose should be reduced
C) Renal function has no effect on insulin clearance, so the hypoglycemia is unrelated to his kidney disease
E) The kidney clears insulin only by glomerular filtration with no tubular component, so eGFR changes are irrelevant
ANSWER: B
Rationale:
The kidney degrades a substantial fraction (roughly 30 to 40 percent) of peripheral insulin, so declining renal function reduces insulin clearance, prolongs insulin action, and raises hypoglycemia risk; the appropriate response is to reduce the insulin dose, with dose reduction generally needed as eGFR (estimated glomerular filtration rate) falls below 30 mL/min/1.73m2.
Option A: Option A is incorrect because renal impairment reduces, not increases, clearance, so the dose should fall.
Option C: Option C is incorrect because the kidney is a major site of insulin clearance, making renal function directly relevant.
Option D: Option D is incorrect because renal impairment does not induce insulin-degrading enzyme to accelerate metabolism; clearance decreases.
Option E: Option E is incorrect because renal insulin clearance involves both glomerular filtration with tubular reabsorption and degradation and peritubular uptake, so declining eGFR matters.
18. [CASE 5 — QUESTION 2]
Continuing with the same patient. He is started on the non-selective beta-blocker propranolol for a separate indication. He soon reports that his hypoglycemic episodes now come on with little warning and seem to last longer. Which explanation best accounts for this change?
A) Propranolol heightens all adrenergic warning symptoms, making hypoglycemia easier to detect
B) Propranolol increases hepatic glycogenolysis, so episodes should resolve faster
C) Propranolol has no interaction with glucose counter-regulation
D) Propranolol selectively abolishes sweating while leaving tremor and palpitations as reliable warnings
E) Propranolol blunts adrenergic warning symptoms such as tremor and palpitations while sweating is relatively preserved, and it can prolong hypoglycemia by blunting hepatic glycogenolysis, so episodes are both less recognizable and slower to resolve
ANSWER: E
Rationale:
Non-selective beta-blockers such as propranolol blunt the adrenergic warning symptoms of hypoglycemia, including tremor and palpitations, while sweating (cholinergically mediated) is relatively preserved; they can also prolong hypoglycemia by blunting hepatic glycogenolysis. This explains episodes that are both harder to recognize and slower to resolve.
Option A: Option A is incorrect because propranolol blunts rather than heightens adrenergic warnings.
Option B: Option B is incorrect because beta-blockade reduces glycogenolysis, prolonging rather than shortening episodes.
Option C: Option C is incorrect because non-selective beta-blockade clearly interacts with glucose counter-regulation and symptom perception.
Option D: Option D is incorrect because it inverts the pattern: sweating tends to be preserved while tremor and palpitations are blunted.
19. [CASE 5 — QUESTION 3]
Continuing with the same patient. One afternoon he skips lunch entirely but takes his usual insulin, and he develops a severe, prolonged hypoglycemic episode. Integrating his reduced renal insulin clearance with the missed meal, which explanation best accounts for the severity?
A) Reduced renal insulin clearance already prolongs his insulin action, and the missed meal removes the carbohydrate the dose anticipated, so the two effects compound to produce a deeper and more prolonged hypoglycemic episode
B) A missed meal raises insulin requirements, so skipping lunch should have caused hyperglycemia
C) Reduced renal clearance and meal timing act on entirely independent systems that cannot combine
D) The missed meal is irrelevant because basal insulin covers meals
E) His renal impairment protects him from hypoglycemia, so the missed meal alone is responsible and the episode should have been mild
ANSWER: A
Rationale:
His reduced renal insulin clearance prolongs insulin action, and skipping a meal removes the carbohydrate his usual dose anticipated; these two effects act in the same direction and compound to produce a deeper and more prolonged hypoglycemic episode.
Option B: Option B is incorrect because a missed meal lowers available glucose against an unchanged insulin dose and predisposes to hypoglycemia, not hyperglycemia.
Option C: Option C is incorrect because both reduced clearance and reduced carbohydrate intake push glucose downward and therefore do combine.
Option D: Option D is incorrect because mealtime bolus insulin, not basal, covers meals, and the bolus given without food drives hypoglycemia.
Option E: Option E is incorrect because reduced renal clearance worsens rather than protects against hypoglycemia.
20. [CASE 5 — QUESTION 4]
Continuing with the same patient. At a family event he drinks several alcoholic beverages with dinner and, hours later overnight, becomes hypoglycemic; a family member's attempt to treat with intramuscular glucagon is relatively ineffective. Integrating alcohol's effect on hepatic glucose handling with the mechanism of glucagon, which explanation is most accurate?
A) Alcohol causes immediate hyperglycemia, so the overnight hypoglycemia is unrelated to drinking
B) Alcohol increases hepatic glucose output, so glucagon should have worked normally
C) Alcohol suppresses hepatic gluconeogenesis, producing characteristically delayed hypoglycemia 4 to 8 hours after ingestion, and glucagon is relatively ineffective in this setting because its glucose-raising action depends on mobilizing hepatic glycogen, which is compromised when glycogen is depleted and gluconeogenesis is simultaneously blocked
D) Glucagon failed only because it was given intramuscularly rather than orally
E) Alcohol accelerates glucagon metabolism, so the dose was cleared before it could act
ANSWER: C
Rationale:
Alcohol suppresses hepatic gluconeogenesis, producing hypoglycemia that is characteristically delayed 4 to 8 hours after ingestion. Glucagon raises glucose mainly by mobilizing hepatic glycogen, so it is relatively ineffective when glycogen stores are depleted and gluconeogenesis is simultaneously blocked, as in this scenario; intravenous dextrose is the more reliable treatment.
Option A: Option A is incorrect because alcohol predisposes to delayed hypoglycemia rather than immediate hyperglycemia.
Option B: Option B is incorrect because alcohol suppresses, not increases, hepatic glucose output.
Option D: Option D is incorrect because glucagon is appropriately given parenterally and failed here because of depleted glycogen, not the route.
Option E: Option E is incorrect because the poor response reflects depleted glycogen and blocked gluconeogenesis, not accelerated glucagon metabolism.
21. [CASE 6 — QUESTION 1]
A 29-year-old woman with type 1 diabetes mellitus presents at 9 weeks of pregnancy. She asks whether insulin is safe for her baby and which preparations are preferred. Which statement is most accurate?
A) Insulin is contraindicated in pregnancy because it readily crosses the placenta and harms the fetus
B) Oral agents should replace insulin in pregnancy because insulin is unsafe for the fetus
C) Insulin should be stopped during the first trimester and resumed only after delivery
D) Insulin is the standard of care in pregnancy and does not cross the placenta in physiologically significant amounts; among the rapid-acting analogs, lispro and aspart have extensive safety data and are preferred
E) Only animal-derived insulins are safe in pregnancy because human and analog insulins cross the placenta
ANSWER: D
Rationale:
Insulin is the standard of care for diabetes in pregnancy and does not cross the placenta in physiologically significant amounts; among the rapid-acting analogs, lispro and aspart have extensive safety data and are preferred.
Option A: Option A is incorrect because insulin does not cross the placenta in significant amounts and is the recommended therapy, not a contraindicated one.
Option B: Option B is incorrect because insulin, not oral agents, is the standard pharmacologic therapy for this patient.
Option C: Option C is incorrect because insulin must be continued throughout pregnancy in type 1 diabetes.
Option E: Option E is incorrect because modern human and analog insulins are appropriate in pregnancy and do not cross the placenta in significant amounts; animal-derived insulin is not required.
22. [CASE 6 — QUESTION 2]
Continuing with the same patient. As her pregnancy advances into the second and third trimesters, the team monitors her insulin requirements. What change should be anticipated, and why?
A) Requirements fall progressively because placental hormones improve insulin sensitivity
B) Requirements rise substantially, often approaching double the pre-pregnancy dose by the third trimester, because placental hormones such as human placental lactogen, cortisol, progesterone, and prolactin produce progressive insulin resistance
C) Requirements remain unchanged throughout pregnancy because the placenta does not affect glucose metabolism
D) Requirements fall in the second trimester and rise only in the final week
E) Requirements are determined solely by diet and are independent of placental hormones
ANSWER: B
Rationale:
Placental hormones, including human placental lactogen, cortisol, progesterone, and prolactin, produce progressive insulin resistance, so insulin requirements rise substantially through the second and third trimesters, often approaching double the pre-pregnancy dose by the third trimester.
Option A: Option A is incorrect because placental hormones increase insulin resistance, raising rather than lowering requirements.
Option C: Option C is incorrect because the placenta strongly affects glucose metabolism through these hormones.
Option D: Option D is incorrect because requirements rise progressively across the second and third trimesters, not only in the final week.
Option E: Option E is incorrect because placental hormone-driven insulin resistance, not diet alone, governs the rising requirements.
23. [CASE 6 — QUESTION 3]
Continuing with the same patient. By the third trimester her insulin dose has nearly doubled. She is about to deliver. What change in insulin requirements should be anticipated at the time of delivery, and what is the appropriate response?
A) Requirements continue to climb after delivery, so the dose should be increased further postpartum
B) Requirements remain at the third-trimester level for several weeks, so no change is needed at delivery
C) Requirements decline gradually over two to three months, so only slow tapering is warranted
D) Requirements are unaffected by delivery because placental hormones persist for weeks postpartum
E) Requirements fall abruptly with delivery of the placenta because the placental hormones driving insulin resistance are suddenly removed, so the insulin dose must be reduced sharply right after delivery to avoid hypoglycemia
ANSWER: E
Rationale:
Delivery of the placenta abruptly removes the placental hormones (human placental lactogen, cortisol, progesterone, prolactin) that drove insulin resistance, so insulin requirements fall steeply within hours; the dose must be reduced sharply right after delivery, often back toward the pre-pregnancy requirement, to prevent hypoglycemia.
Option A: Option A is incorrect because requirements drop, not rise, once the placenta is delivered.
Option B: Option B is incorrect because the third-trimester elevation does not persist after placental removal.
Option C: Option C is incorrect because the fall is abrupt at delivery rather than a gradual months-long taper.
Option D: Option D is incorrect because the placental hormone effect resolves rapidly once the placenta is delivered rather than persisting for weeks.
24. [CASE 6 — QUESTION 4]
Continuing with the same patient. Before pregnancy she had been using insulin degludec as her basal insulin. She asks whether she can continue it during pregnancy. What is the most appropriate guidance regarding basal insulin selection in pregnancy?
A) Degludec is not recommended in pregnancy owing to insufficient safety data, so an alternative basal insulin with adequate pregnancy data should be used
B) Degludec is the preferred basal insulin in pregnancy because of its long duration
C) All basal insulins are contraindicated in pregnancy, so she should use only rapid-acting insulin
D) Degludec must be continued because switching basal insulin in pregnancy is unsafe
E) Basal insulin is unnecessary in pregnancy because placental hormones provide glycemic control
ANSWER: A
Rationale:
Insulin degludec is not recommended in pregnancy because of insufficient safety data; an alternative basal insulin with adequate pregnancy data should be selected. Human insulins and the analogs lispro and aspart have extensive data, while glargine and detemir are used in practice with apparent safety.
Option B: Option B is incorrect because degludec is specifically not recommended in pregnancy despite its long duration.
Option C: Option C is incorrect because basal insulin is needed in type 1 diabetes, and basal insulins are not categorically contraindicated in pregnancy.
Option D: Option D is incorrect because the appropriate action is to switch away from degludec to an agent with adequate data, not to continue it.
Option E: Option E is incorrect because basal insulin remains essential in pregnancy; placental hormones increase insulin resistance rather than providing glycemic control.
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