Pharmacology Quiz: Sulfonylureas
20 questions · exam conditions
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SulfonylureasQuestion 1 of 20

A 58-year-old truck driver with type 2 diabetes is being initiated on glipizide. He reports that his meal schedule is often unpredictable due to his long-haul routes.

Which piece of counseling is most critical to provide this patient to minimize his risk of a serious adverse event related to glipizide?

Monitor blood pressure daily as the medication can cause fluid retention.
Ensure you take the medication with a full glass of water for better absorption.
If you must skip a meal, you should also skip your dose of glipizide for that meal.
Avoid taking non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief.
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Pharmacology Quiz

Pharmacology Quiz: Sulfonylureas

Practice Sulfonylureas in Pharmacology with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Sulfonylureas, giving you a quick way to practice the rules, question types, and explanations that matter most for Pharmacology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A 58-year-old truck driver with type 2 diabetes is being initiated on glipizide. He reports that his meal schedule is often unpredictable due to his long-haul routes.

Which piece of counseling is most critical to provide this patient to minimize his risk of a serious adverse event related to glipizide?

  1. Monitor blood pressure daily as the medication can cause fluid retention.
  2. Ensure you take the medication with a full glass of water for better absorption.
  3. If you must skip a meal, you should also skip your dose of glipizide for that meal. (correct answer)
  4. Avoid taking non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief.
Explanation: Sulfonylureas stimulate insulin release regardless of food intake. Taking a dose without a subsequent meal is a very common cause of severe hypoglycemia. For a patient with an unpredictable meal schedule, the most important counseling point is to align medication administration with food intake, which may mean skipping a dose if a meal is skipped. While NSAIDs can potentially potentiate hypoglycemia, the risk from a skipped meal is far more direct and common. Fluid retention is not a primary side effect, and while taking with water is good practice, it is not the most critical safety instruction.

Question 2

When managing a patient with severe, recurrent hypoglycemia secondary to a sulfonylurea overdose, administration of octreotide is considered. What is the mechanism by which octreotide alleviates this condition?

  1. It inhibits the release of insulin from pancreatic beta-cells. (correct answer)
  2. It stimulates hepatic glycogenolysis and gluconeogenesis to raise plasma glucose.
  3. It directly antagonizes the sulfonylurea receptor on the pancreatic beta-cell.
  4. It enhances the renal clearance of the offending sulfonylurea agent.
Explanation: When you encounter questions about antidotes for drug overdoses, focus on understanding the specific mechanism by which the antidote counteracts the toxic effect, rather than assuming it works through general detoxification pathways. Sulfonylureas cause hypoglycemia by binding to ATP-sensitive potassium channels on pancreatic beta-cells, leading to continuous insulin release regardless of blood glucose levels. Octreotide, a synthetic somatostatin analog, directly inhibits insulin secretion from these beta-cells by binding to somatostatin receptors and reducing intracellular cAMP levels. This mechanism makes octreotide particularly effective for sulfonylurea-induced hypoglycemia because it addresses the root problem—excessive insulin release—rather than just treating the resulting low glucose. Looking at the incorrect options: Option B describes the mechanism of glucagon, not octreotide. While glucagon does stimulate hepatic glucose production, octreotide works by stopping the source of excess insulin rather than counteracting its effects through glucose production. Option C suggests direct receptor antagonism, but octreotide doesn't block sulfonylurea receptors—it works through a separate somatostatin receptor pathway to achieve the same end result of reduced insulin secretion. Option D proposes enhanced renal clearance, but octreotide has no significant effect on drug elimination; it's a functional antidote that counteracts the drug's effects while it remains in the system. Remember that octreotide is specifically indicated for sulfonylurea overdoses precisely because it targets insulin secretion—the mechanism underlying sulfonylurea toxicity. This makes it more targeted and effective than general supportive measures alone.

Question 3

A 75-year-old female with T2DM is managed with glyburide. She is hospitalized for pneumonia and started on broad-spectrum antibiotics. Her oral intake is poor. On day 3 of admission, she is found to be hypoglycemic. Her serum creatinine is 1.5 mg/dL (baseline 1.0 mg/dL).

Which combination of factors provides the most complete explanation for her hypoglycemic episode?

  1. Antibiotic-induced reduction in gut flora and acute kidney injury.
  2. Poor oral intake and decreased insulin resistance from acute illness.
  3. A direct interaction between the antibiotic and glyburide.
  4. Acute kidney injury and poor oral intake. (correct answer)
Explanation: When you encounter hypoglycemia in hospitalized diabetic patients on sulfonylureas like glyburide, think systematically about factors that could either increase drug levels or decrease glucose intake/production. This patient's hypoglycemia results from two key factors working together. First, her poor oral intake means reduced glucose availability while glyburide continues stimulating insulin release from pancreatic beta cells. Second, her acute kidney injury (creatinine rose from 1.0 to 1.5 mg/dL) impairs glyburide clearance. Glyburide is metabolized to active metabolites that are renally excreted, so kidney dysfunction allows these hypoglycemic metabolites to accumulate. This combination of decreased glucose input and increased effective drug activity creates the perfect storm for hypoglycemia. Answer D correctly identifies both contributing factors: acute kidney injury and poor oral intake. Answer A incorrectly suggests antibiotic-induced gut flora changes cause hypoglycemia. While antibiotics can alter gut microbiota, this doesn't significantly affect glucose metabolism or glyburide action in the acute setting. Answer B mentions decreased insulin resistance from acute illness. However, acute illness typically increases insulin resistance due to stress hormones and inflammatory mediators, which would tend to raise, not lower, blood glucose. Answer C proposes a direct drug interaction between antibiotics and glyburide. While some antibiotics can interact with certain medications, broad-spectrum antibiotics don't typically have clinically significant direct interactions with glyburide that would cause hypoglycemia. Remember: sulfonylurea-induced hypoglycemia often involves multiple factors. Always consider both pharmacokinetic changes (drug clearance) and reduced glucose intake in hospitalized patients.

Question 4

In the event of an intentional overdose of a long-acting sulfonylurea, why is a patient's risk of severe hypoglycemia markedly higher than that of a patient who overdoses on a similar quantity of rapid-acting insulin?

  1. Sulfonylureas cause a greater peak insulin secretion than exogenous insulin.
  2. Insulin is subject to rapid first-pass metabolism, unlike sulfonylureas.
  3. Sulfonylureas simultaneously inhibit glucagon release, preventing a counter-regulatory response.
  4. The long half-life of the sulfonylurea leads to continuous endogenous insulin secretion. (correct answer)
Explanation: When comparing overdose risks between different diabetes medications, you need to consider both the mechanism of action and the pharmacokinetics of each drug. Long-acting sulfonylureas like glyburide have extended half-lives (up to 24 hours) and work by binding to pancreatic beta cells, forcing them to continuously secrete insulin. In an overdose, this creates a prolonged state where your pancreas keeps pumping out insulin for many hours, leading to sustained and severe hypoglycemia that's difficult to reverse. The correct answer is D because this continuous endogenous insulin production from the long half-life is what makes sulfonylurea overdoses so dangerous. Option A is incorrect because sulfonylureas don't cause greater peak insulin levels than exogenous insulin - the issue is duration, not magnitude. Option B misunderstands insulin metabolism; while insulin does undergo hepatic metabolism, it's not subject to significant first-pass metabolism since it's typically injected subcutaneously, bypassing the GI tract entirely. Option C incorrectly suggests sulfonylureas inhibit glucagon - they primarily work on insulin-secreting beta cells, not glucagon-producing alpha cells. The key difference is that with insulin overdose, once the injected insulin is metabolized (relatively quickly), the hypoglycemic effect ends. With sulfonylureas, your own pancreas becomes the problem, continuing to overproduce insulin until the drug is cleared from your system. Remember: sulfonylurea toxicity = prolonged endogenous insulin secretion. This is why these overdoses often require hospitalization with continuous glucose monitoring and dextrose infusions.

Question 5

A 70-year-old patient with type 2 diabetes, hypertension, and angina is treated with metformin, glipizide, and metoprolol. He presents to his physician complaining of recent episodes of confusion and sweating, which he did not initially recognize as significant. His wife checked his glucose during one episode and found it to be 48 mg/dL.

Which aspect of the patient's regimen is most likely contributing to his lack of awareness of these hypoglycemic episodes?

  1. Glipizide's effect on CNS glucose transport.
  2. Metformin's suppression of hepatic gluconeogenesis.
  3. Metoprolol's blockade of beta-adrenergic receptors. (correct answer)
  4. Age-related decline in autonomic nervous system function.
Explanation: The early warning signs of hypoglycemia (tachycardia, palpitations, tremor, anxiety) are mediated by the sympathetic nervous system's release of catecholamines acting on beta-adrenergic receptors. Metoprolol, a beta-blocker, blunts these autonomic symptoms. This can lead to 'hypoglycemia unawareness,' where the patient does not experience the typical warning signs and may progress directly to more severe neuroglycopenic symptoms like confusion. While age-related decline can contribute, the pharmacologic effect of the beta-blocker is the most direct and modifiable cause.

Question 6

The affinity of second-generation sulfonylureas (e.g., glyburide, glipizide) for the SUR1 subunit of the K-ATP channel is significantly higher than that of first-generation agents (e.g., tolbutamide). What is the primary clinical consequence of this higher affinity?

  1. A significant increase in pharmacologic potency. (correct answer)
  2. A lower incidence of cardiovascular side effects.
  3. A reduced likelihood of disulfiram-like reactions.
  4. Improved selectivity for pancreatic over cardiac K-ATP channels.
Explanation: Higher binding affinity means that a lower concentration of the drug is required to achieve the same degree of receptor occupation and, consequently, the same pharmacologic effect (K-ATP channel closure). This translates directly to higher potency, which is why second-generation sulfonylureas are administered in much lower milligram doses than first-generation agents. While there are other differences between the generations, the most direct consequence of the increased binding affinity is the increase in potency.

Question 7

A patient with type 2 diabetes managed on maximum-dose metformin and a stable dose of glyburide for the past two years presents with recurrent morning hypoglycemia. A review of systems is negative except for recent initiation of a new medication for hyperlipidemia one month ago.

Initiation of which of the following medications is the most likely cause for this change in glycemic control?

  1. Atorvastatin
  2. Ezetimibe
  3. Colesevelam
  4. Gemfibrozil (correct answer)
Explanation: Gemfibrozil, a fibrate, can increase the hypoglycemic effects of sulfonylureas. The mechanism is complex but includes displacement of the sulfonylurea from plasma protein binding sites (increasing the free, active fraction) and potential inhibition of metabolism. This interaction can lead to a significant increase in the drug's effect, precipitating hypoglycemia even in a previously stable patient. Statins, ezetimibe, and colesevelam do not have this significant interaction with sulfonylureas.

Question 8

A patient with type 2 diabetes is treated with a sulfonylurea. Which of the following physiological events is bypassed by the drug's mechanism of action, contributing directly to its risk of causing hypoglycemia?

  1. Glucose entry into the pancreatic beta-cell via GLUT2 transporters.
  2. Phosphorylation of glucose by glucokinase within the beta-cell.
  3. Generation of ATP from glucose metabolism via glycolysis and oxidative phosphorylation. (correct answer)
  4. Depolarization of the beta-cell membrane via voltage-gated calcium channels.
Explanation: Normally, glucose enters the beta-cell, is metabolized to produce ATP, and the resulting increase in the ATP/ADP ratio closes the K-ATP channel. Sulfonylureas bind directly to the SUR1 subunit of the K-ATP channel and cause it to close, mimicking the effect of a high ATP/ADP ratio. This means the drug bypasses the entire glucose sensing and metabolism pathway (glucose entry, phosphorylation, ATP generation). The subsequent steps, membrane depolarization and calcium influx, are still required for insulin release but are triggered by the drug's action on the channel, not by glucose metabolism. Bypassing the ATP generation step is what makes the insulin release glucose-independent.

Question 9

A patient taking a daily morning dose of a long-acting sulfonylurea presents with neuroglycopenic symptoms in the late afternoon. Laboratory tests confirm hypoglycemia. The patient reports having eaten a normal breakfast and lunch. Which additional factor is most likely to have precipitated this event?

  1. Co-ingestion of a high-fat meal at lunch.
  2. A bout of unplanned, strenuous physical activity. (correct answer)
  3. Consumption of several cups of black coffee.
  4. A mild upper respiratory tract infection.
Explanation: In a patient on a sulfonylurea, insulin levels are elevated regardless of glucose levels. Strenuous physical activity increases glucose uptake by skeletal muscles, independent of insulin. The combination of high circulating insulin (from the sulfonylurea) and increased peripheral glucose utilization (from exercise) can lead to a rapid and severe drop in blood glucose. A high-fat meal might delay gastric emptying but is less likely to cause hypoglycemia. Mild illness often causes hyperglycemia due to stress hormones. Caffeine has minimal direct effect on glucose in this context.

Question 10

The affinity of second-generation sulfonylureas (e.g., glyburide, glipizide) for the SUR1 subunit of the K-ATP channel is significantly higher than that of first-generation agents (e.g., tolbutamide). What is the primary clinical consequence of this higher affinity?

  1. A significant increase in pharmacologic potency. (correct answer)
  2. A lower incidence of cardiovascular side effects.
  3. A reduced likelihood of disulfiram-like reactions.
  4. Improved selectivity for pancreatic over cardiac K-ATP channels.
Explanation: Higher binding affinity means that a lower concentration of the drug is required to achieve the same degree of receptor occupation and, consequently, the same pharmacologic effect (K-ATP channel closure). This translates directly to higher potency, which is why second-generation sulfonylureas are administered in much lower milligram doses than first-generation agents. While there are other differences between the generations, the most direct consequence of the increased binding affinity is the increase in potency.

Question 11

A 68-year-old patient taking glimepiride for type 2 diabetes has been fasting for a religious observance. He presents to the clinic with symptoms of lightheadedness and a fingerstick glucose of 55 mg/dL. This event occurs because glimepiride's action on the beta-cell K-ATP channel is independent of which intracellular signal?

  1. The influx of extracellular calcium ions.
  2. The membrane potential of the beta-cell.
  3. The exocytosis of insulin-containing granules.
  4. The intracellular ATP to ADP ratio. (correct answer)
Explanation: When you encounter questions about sulfonylureas like glimepiride, focus on understanding their mechanism of action versus normal physiological insulin release. This distinction is crucial for predicting their effects, especially during fasting states. Sulfonylureas work by directly binding to and blocking K-ATP channels on pancreatic beta-cells, forcing these channels closed regardless of the cell's metabolic state. This is why glimepiride causes hypoglycemia during fasting—it bypasses the normal glucose-sensing mechanism that would otherwise prevent insulin release when glucose is low. The correct answer is D because glimepiride's action is independent of the intracellular ATP to ADP ratio. Normally, when glucose enters beta-cells, it's metabolized to produce ATP, and the rising ATP/ADP ratio closes K-ATP channels. However, glimepiride directly blocks these channels without needing this metabolic signal, which is why patients can develop hypoglycemia even when fasting. Choice A is incorrect because once K-ATP channels close (whether naturally or due to glimepiride), calcium influx still occurs and is essential for insulin release. Choice B is wrong because glimepiride still depends on membrane depolarization—blocking K+ efflux depolarizes the membrane, opening voltage-gated calcium channels. Choice C is incorrect because exocytosis of insulin granules remains the final step in glimepiride's mechanism, triggered by the calcium influx. Remember: sulfonylureas cause hypoglycemia precisely because they uncouple insulin release from glucose sensing. Always consider this risk in fasting patients or those with irregular eating patterns.

Question 12

An 82-year-old resident of a nursing home is found unresponsive. Her fingerstick glucose is 35 mg/dL. Her medication list includes metformin and glyburide. She is given intravenous 50% dextrose, and her mental status improves. She is transferred to the emergency department for further management.

Which of the following interventions is most critical to prevent recurrence of hypoglycemia in this patient over the next 24 hours?

  1. Administering a single dose of intramuscular glucagon upon ED arrival.
  2. Providing a meal with complex carbohydrates once she is fully alert.
  3. Initiating a continuous intravenous infusion of 10% dextrose. (correct answer)
  4. Discontinuing glyburide and monitoring glucose every 4 hours.
Explanation: Sulfonylurea-induced hypoglycemia can be profound and prolonged, especially with long-acting agents like glyburide in elderly patients who may have reduced renal clearance. A single bolus of dextrose or a meal is often insufficient to counteract the continuous, glucose-independent insulin secretion stimulated by the drug. A continuous infusion of dextrose is required to maintain euglycemia. Glucagon may be used for initial resuscitation but its effect is transient. While discontinuing the drug and monitoring are necessary, they are not sufficient interventions to prevent recurrent hypoglycemia.

Question 13

An 82-year-old resident of a nursing home is found unresponsive. Her fingerstick glucose is 35 mg/dL. Her medication list includes metformin and glyburide. She is given intravenous 50% dextrose, and her mental status improves. She is transferred to the emergency department for further management.

Which of the following interventions is most critical to prevent recurrence of hypoglycemia in this patient over the next 24 hours?

  1. Administering a single dose of intramuscular glucagon upon ED arrival.
  2. Providing a meal with complex carbohydrates once she is fully alert.
  3. Initiating a continuous intravenous infusion of 10% dextrose. (correct answer)
  4. Discontinuing glyburide and monitoring glucose every 4 hours.
Explanation: Sulfonylurea-induced hypoglycemia can be profound and prolonged, especially with long-acting agents like glyburide in elderly patients who may have reduced renal clearance. A single bolus of dextrose or a meal is often insufficient to counteract the continuous, glucose-independent insulin secretion stimulated by the drug. A continuous infusion of dextrose is required to maintain euglycemia. Glucagon may be used for initial resuscitation but its effect is transient. While discontinuing the drug and monitoring are necessary, they are not sufficient interventions to prevent recurrent hypoglycemia.

Question 14

A patient is brought to the emergency department with confusion and a plasma glucose of 40 mg/dL. An investigation is initiated to determine the cause. The patient has a history of type 2 diabetes, but his medication list is unavailable.

Which of the following laboratory findings would most strongly support surreptitious use of a sulfonylurea as the cause of hypoglycemia, rather than exogenous insulin administration?

  1. Low plasma insulin level
  2. Elevated plasma C-peptide level (correct answer)
  3. Presence of ketones in the urine
  4. Suppressed plasma glucagon level
Explanation: When pancreatic beta-cells release insulin, they cleave proinsulin into insulin and C-peptide in equimolar amounts. Sulfonylureas stimulate the endogenous release of insulin from the pancreas. Therefore, in sulfonylurea-induced hypoglycemia, both insulin and C-peptide levels will be elevated. In contrast, if a patient injects exogenous insulin, their plasma insulin level will be high, but their endogenous insulin secretion will be suppressed by the hypoglycemia, resulting in a low C-peptide level. Therefore, an elevated C-peptide level is the key differentiator.

Question 15

A 65-year-old female with well-controlled type 2 diabetes on glimepiride 4 mg daily develops a severe case of onychomycosis. She is prescribed a 12-week course of oral terbinafine by her podiatrist. Two weeks later, she experiences several episodes of symptomatic hypoglycemia, with fingerstick glucose readings in the 50s mg/dL, despite no changes in her diet or exercise.

Her new prescription for an antifungal is a more likely cause of her hypoglycemia if the agent prescribed was not terbinafine, but which of the following?

  1. Nystatin
  2. Fluconazole (correct answer)
  3. Amphotericin B
  4. Caspofungin
Explanation: Glimepiride, like many other sulfonylureas, is metabolized by the cytochrome P450 enzyme CYP2C9. Fluconazole is a potent inhibitor of CYP2C9. Co-administration of fluconazole would decrease the metabolism of glimepiride, leading to higher plasma concentrations and an increased risk of hypoglycemia. Terbinafine is a CYP2D6 inhibitor and does not significantly interact with glimepiride. Nystatin is not systemically absorbed. Amphotericin B and caspofungin are not significant CYP2C9 inhibitors and work via different mechanisms.

Question 16

A patient taking a daily morning dose of a long-acting sulfonylurea presents with neuroglycopenic symptoms in the late afternoon. Laboratory tests confirm hypoglycemia. The patient reports having eaten a normal breakfast and lunch. Which additional factor is most likely to have precipitated this event?

  1. Co-ingestion of a high-fat meal at lunch.
  2. A bout of unplanned, strenuous physical activity. (correct answer)
  3. Consumption of several cups of black coffee.
  4. A mild upper respiratory tract infection.
Explanation: In a patient on a sulfonylurea, insulin levels are elevated regardless of glucose levels. Strenuous physical activity increases glucose uptake by skeletal muscles, independent of insulin. The combination of high circulating insulin (from the sulfonylurea) and increased peripheral glucose utilization (from exercise) can lead to a rapid and severe drop in blood glucose. A high-fat meal might delay gastric emptying but is less likely to cause hypoglycemia. Mild illness often causes hyperglycemia due to stress hormones. Caffeine has minimal direct effect on glucose in this context.

Question 17

A 62-year-old male with type 2 diabetes and alcoholic cirrhosis (Child-Pugh class B) is managed with glimepiride. He is admitted to the hospital with a hypoglycemic seizure. His blood glucose on arrival is 28 mg/dL.

What is the most likely pathophysiologic reason for the severity of his hypoglycemia?

  1. Impaired hepatic metabolism of glimepiride increases its half-life. (correct answer)
  2. Reduced glycogen stores limit the counter-regulatory response.
  3. Decreased synthesis of albumin leads to higher free drug concentration.
  4. Malnutrition associated with cirrhosis reduces insulin resistance.
Explanation: While all the listed factors can contribute to hypoglycemia in a patient with cirrhosis, the most direct pharmacologic reason related to the sulfonylurea is impaired metabolism. Glimepiride is extensively metabolized by the liver. In a patient with significant hepatic dysfunction, the clearance of the drug is reduced, leading to accumulation and a prolonged, potent hypoglycemic effect. This accumulation is the primary driver of the severe event. Reduced glycogen stores (B) and higher free drug fraction (C) are also contributing factors but are secondary to the primary issue of drug accumulation from impaired metabolism.

Question 18

A 70-year-old patient with type 2 diabetes, hypertension, and angina is treated with metformin, glipizide, and metoprolol. He presents to his physician complaining of recent episodes of confusion and sweating, which he did not initially recognize as significant. His wife checked his glucose during one episode and found it to be 48 mg/dL.

Which aspect of the patient's regimen is most likely contributing to his lack of awareness of these hypoglycemic episodes?

  1. Glipizide's effect on CNS glucose transport.
  2. Metformin's suppression of hepatic gluconeogenesis.
  3. Metoprolol's blockade of beta-adrenergic receptors. (correct answer)
  4. Age-related decline in autonomic nervous system function.
Explanation: The early warning signs of hypoglycemia (tachycardia, palpitations, tremor, anxiety) are mediated by the sympathetic nervous system's release of catecholamines acting on beta-adrenergic receptors. Metoprolol, a beta-blocker, blunts these autonomic symptoms. This can lead to 'hypoglycemia unawareness,' where the patient does not experience the typical warning signs and may progress directly to more severe neuroglycopenic symptoms like confusion. While age-related decline can contribute, the pharmacologic effect of the beta-blocker is the most direct and modifiable cause.

Question 19

When managing a patient with severe, recurrent hypoglycemia secondary to a sulfonylurea overdose, administration of octreotide is considered. What is the mechanism by which octreotide alleviates this condition?

  1. It inhibits the release of insulin from pancreatic beta-cells. (correct answer)
  2. It stimulates hepatic glycogenolysis and gluconeogenesis to raise plasma glucose.
  3. It directly antagonizes the sulfonylurea receptor on the pancreatic beta-cell.
  4. It enhances the renal clearance of the offending sulfonylurea agent.
Explanation: When you encounter questions about antidotes for drug overdoses, focus on understanding the specific mechanism by which the antidote counteracts the toxic effect, rather than assuming it works through general detoxification pathways. Sulfonylureas cause hypoglycemia by binding to ATP-sensitive potassium channels on pancreatic beta-cells, leading to continuous insulin release regardless of blood glucose levels. Octreotide, a synthetic somatostatin analog, directly inhibits insulin secretion from these beta-cells by binding to somatostatin receptors and reducing intracellular cAMP levels. This mechanism makes octreotide particularly effective for sulfonylurea-induced hypoglycemia because it addresses the root problem—excessive insulin release—rather than just treating the resulting low glucose. Looking at the incorrect options: Option B describes the mechanism of glucagon, not octreotide. While glucagon does stimulate hepatic glucose production, octreotide works by stopping the source of excess insulin rather than counteracting its effects through glucose production. Option C suggests direct receptor antagonism, but octreotide doesn't block sulfonylurea receptors—it works through a separate somatostatin receptor pathway to achieve the same end result of reduced insulin secretion. Option D proposes enhanced renal clearance, but octreotide has no significant effect on drug elimination; it's a functional antidote that counteracts the drug's effects while it remains in the system. Remember that octreotide is specifically indicated for sulfonylurea overdoses precisely because it targets insulin secretion—the mechanism underlying sulfonylurea toxicity. This makes it more targeted and effective than general supportive measures alone.

Question 20

A patient with type 2 diabetes managed on maximum-dose metformin and a stable dose of glyburide for the past two years presents with recurrent morning hypoglycemia. A review of systems is negative except for recent initiation of a new medication for hyperlipidemia one month ago.

Initiation of which of the following medications is the most likely cause for this change in glycemic control?

  1. Atorvastatin
  2. Ezetimibe
  3. Colesevelam
  4. Gemfibrozil (correct answer)
Explanation: Gemfibrozil, a fibrate, can increase the hypoglycemic effects of sulfonylureas. The mechanism is complex but includes displacement of the sulfonylurea from plasma protein binding sites (increasing the free, active fraction) and potential inhibition of metabolism. This interaction can lead to a significant increase in the drug's effect, precipitating hypoglycemia even in a previously stable patient. Statins, ezetimibe, and colesevelam do not have this significant interaction with sulfonylureas.