USMLE Step 2 Quiz: Diabetes Mellitus And Glycemic Management

What this quiz covers

This quiz focuses on Diabetes Mellitus And Glycemic Management, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 2.

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.

Question 1

1. Administer a bolus of regular insulin intravenously
2. Start a continuous infusion of regular insulin
3. Administer intravenous potassium chloride (correct answer)
4. Administer intravenous sodium bicarbonate

Explanation: This patient has diabetic ketoacidosis (DKA). The initial management includes aggressive intravenous fluid resuscitation, which has been started. The next crucial step is to address the potassium level before starting insulin. Although the serum potassium is low-normal, the patient has a significant total body potassium deficit due to transcellular shifts and urinary losses. Insulin therapy will drive potassium into cells, worsening the hypokalemia and potentially causing life-threatening arrhythmias. Therefore, if the initial serum potassium is less than 3.3 mEq/L, insulin should be held, and potassium should be repleted first. In this case, with a potassium of 3.1 mEq/L, administering intravenous potassium chloride is the correct next step. Insulin should only be started once the potassium is >3.3 mEq/L.

Question 2

1. Continue sliding-scale insulin with a higher dose
2. Initiate a scheduled basal-bolus insulin regimen (correct answer)
3. Start an intravenous insulin infusion
4. Restart her home dose of metformin

Explanation: For non-critically ill hospitalized patients with persistent hyperglycemia (e.g., >180 mg/dL), a scheduled basal-bolus insulin regimen is the standard of care. This approach provides a physiologic insulin replacement with a long-acting (basal) insulin to cover basal metabolic needs and a rapid-acting (bolus) insulin to cover nutritional intake. Sliding-scale insulin as monotherapy is reactive rather than proactive and is associated with poor glycemic control and higher rates of hyperglycemia. An intravenous insulin infusion is typically reserved for critically ill patients in the ICU. Restarting metformin is inappropriate in an acutely ill patient with poor oral intake and risk of renal dysfunction.

Question 3

1. Normal glucose tolerance
2. Impaired fasting glucose
3. Gestational diabetes mellitus (correct answer)
4. Overt diabetes in pregnancy

Explanation: The diagnosis of gestational diabetes mellitus (GDM) using the 100-gram OGTT is made if at least two of the four plasma glucose values are met or exceeded. The typical cutoffs are: Fasting ≥95 mg/dL, 1-hour ≥180 mg/dL, 2-hour ≥155 mg/dL, and 3-hour ≥140 mg/dL. This patient's 1-hour value (200 mg/dL) and 2-hour value (165 mg/dL) are both above the threshold. Since two criteria are met, the diagnosis is GDM. Her fasting glucose is normal, so she does not have impaired fasting glucose. Overt diabetes would be diagnosed with fasting glucose ≥126 mg/dL or random glucose ≥200 mg/dL with symptoms.

Question 4

1. Stop taking all insulin until you can eat again
2. Continue your long-acting (basal) insulin and take supplemental short-acting insulin for hyperglycemia (correct answer)
3. Take only half of your usual long-acting insulin dose and hold the short-acting insulin
4. Go to the emergency department immediately for intravenous fluids

Explanation: During periods of illness ('sick days'), patients with type 1 diabetes have increased counter-regulatory hormones, leading to increased insulin resistance and hyperglycemia, even with poor oral intake. It is critical to never stop basal insulin, as this can quickly precipitate DKA. The correct advice is to continue the long-acting (basal) insulin, check blood glucose and ketones frequently, stay hydrated, and use supplemental short-acting insulin (correction doses) to manage hyperglycemia. While he may eventually need to go to the emergency department if vomiting persists or ketones worsen, the initial advice should be focused on proper self-management.

Question 5

1. Insulin glargine
2. Glyburide
3. Empagliflozin (correct answer)
4. Sitagliptin

Explanation: For patients with type 2 diabetes and comorbid heart failure with reduced ejection fraction (HFrEF), SGLT2 inhibitors (e.g., empagliflozin, dapagliflozin) have been shown to reduce the risk of cardiovascular death and hospitalizations for heart failure, independent of their glucose-lowering effect. Therefore, adding empagliflozin would provide the most significant benefit for his cardiac condition. Insulin glargine, glyburide, and sitagliptin effectively lower glucose but do not have the specific proven cardiovascular and heart failure benefits of SGLT2 inhibitors. In fact, some older medications like thiazolidinediones are contraindicated in heart failure.

Question 6

1. Take both metformin and glipizide as usual
2. Take the metformin but hold the glipizide
3. Take the glipizide but hold the metformin
4. Hold both metformin and glipizide (correct answer)

Explanation: For patients undergoing surgery who are NPO, oral hypoglycemic agents should generally be held on the morning of the procedure to prevent hypoglycemia. Sulfonylureas like glipizide carry a significant risk of hypoglycemia in a fasting state. Metformin is held due to the risk of lactic acidosis in the setting of potential renal dysfunction or hypoperfusion related to surgery and anesthesia. Therefore, the safest approach is to hold both medications. Inpatient glycemic control will be managed with insulin as needed, typically with a correction scale or a basal-bolus regimen if hyperglycemia is significant.

Question 7

1. Administer intramuscular glucagon and discharge
2. Provide a meal with complex carbohydrates and observe for 4 hours
3. Admit the patient and start a continuous intravenous dextrose infusion (correct answer)
4. Discontinue glyburide and schedule a follow-up appointment

Explanation: This patient is experiencing recurrent and profound hypoglycemia secondary to a long-acting sulfonylurea (glyburide). Due to the long half-life of these medications, a single bolus of dextrose is often insufficient, and rebound hypoglycemia is common, as seen in this case. The risk is particularly high in the elderly and those with renal insufficiency. The standard of care for sulfonylurea-induced hypoglycemia is hospital admission for continuous intravenous dextrose infusion (e.g., D10W) and frequent glucose monitoring for at least 24-48 hours. Discharging the patient would be unsafe. Octreotide, which inhibits insulin secretion, may also be considered as an adjunct.

Question 8

1. Increase the dose of metformin
2. Add dapagliflozin (correct answer)
3. Add pioglitazone
4. Switch sitagliptin to liraglutide

Explanation: For patients with type 2 diabetes and diabetic kidney disease with albuminuria, SGLT2 inhibitors (e.g., dapagliflozin, empagliflozin, canagliflozin) are recommended to reduce the risk of CKD progression and cardiovascular events. These agents have proven renal-protective effects independent of their glucose-lowering capacity and are indicated for patients with an eGFR >30. While GLP-1 receptor agonists like liraglutide also have some renal and cardiovascular benefits, the evidence for slowing CKD progression is strongest for SGLT2 inhibitors in this population. Increasing metformin is not advisable with a reduced eGFR. Pioglitazone does not have the same proven renal-protective effects and can cause fluid retention.

Question 9

1. Stop the insulin infusion and start a sliding-scale subcutaneous regimen
2. Administer the first dose of long-acting subcutaneous insulin and stop the infusion 1-2 hours later (correct answer)
3. Stop the insulin infusion and administer the first dose of long-acting subcutaneous insulin simultaneously
4. Taper the insulin infusion by 0.5 units/hour every hour until it is off

Explanation: The proper transition from an IV insulin infusion to a subcutaneous regimen requires an overlap between the two methods to prevent a gap in insulin coverage, which could lead to rebound hyperglycemia and ketosis. Intravenous regular insulin has a very short half-life. Long-acting basal insulins (e.g., glargine, detemir) take 1-2 hours to begin working. Therefore, the correct procedure is to administer the first dose of subcutaneous long-acting insulin and then continue the IV infusion for another 1-2 hours before discontinuing it. Stopping the infusion simultaneously with or before the subcutaneous injection would create a period of insulin deficiency.

Question 10

1. Hyperosmolar hyperglycemic state
2. Gastroenteritis with metabolic acidosis
3. Euglycemic diabetic ketoacidosis (correct answer)
4. Lactic acidosis from metformin

Explanation: This patient presents with a high anion gap metabolic acidosis and ketosis, which are hallmarks of DKA. However, her blood glucose is only mildly elevated (190 mg/dL). This constellation of findings in a patient taking an SGLT2 inhibitor (empagliflozin) is characteristic of euglycemic diabetic ketoacidosis (eDKA). SGLT2 inhibitors promote glucosuria, which can mask the significant hyperglycemia typically seen in DKA. Precipitating factors often include illness, surgery, or very low carbohydrate intake. HHS is characterized by severe hyperglycemia and hyperosmolality without significant acidosis. While gastroenteritis can cause acidosis, it would not typically cause ketosis of this magnitude. Metformin-associated lactic acidosis is possible but less likely to present with significant ketosis.

Question 11

1. Hypoglycemia
2. Weight gain
3. Gastrointestinal distress (correct answer)
4. Lactic acidosis

Explanation: The most common adverse effects of metformin are gastrointestinal, including diarrhea, nausea, abdominal cramping, and bloating. These symptoms are often dose-dependent and can be minimized by starting with a low dose and titrating slowly, and by taking the medication with food. Hypoglycemia is very rare when metformin is used as monotherapy. Metformin is weight-neutral or may cause modest weight loss, not weight gain. Lactic acidosis is a rare but serious potential side effect, typically occurring in patients with significant renal impairment (e.g., eGFR <30), acute illness, or other contraindications, not in patients with normal renal function.

Question 12

1. Increased production of human placental lactogen (correct answer)
2. Decreased maternal cortisol levels
3. Increased fetal glucose utilization
4. Decreased glomerular filtration rate

Explanation: During the second and third trimesters of pregnancy, placental hormones, particularly human placental lactogen (hPL), but also progesterone and cortisol, increase significantly. These hormones are diabetogenic, meaning they induce a state of insulin resistance in the mother to ensure an adequate supply of glucose for the growing fetus. In a woman with type 1 diabetes, this progressive insulin resistance necessitates a significant increase in exogenous insulin doses to maintain euglycemia. Fetal glucose utilization increases, but the primary driver of maternal insulin needs is the hormonal induction of insulin resistance. Maternal cortisol levels actually increase, and GFR increases in pregnancy.

Question 13

1. Serum insulin level
2. Anti-glutamic acid decarboxylase antibodies (correct answer)
3. Fasting lipid panel
4. 24-hour urine microalbumin

Explanation: This patient's presentation with significant weight loss, ketonuria, and a normal BMI, despite being an adult, is highly suggestive of type 1 diabetes (or Latent Autoimmune Diabetes in Adults - LADA), rather than type 2. The presence of a personal or family history of other autoimmune diseases (like Hashimoto thyroiditis) further increases this suspicion. Testing for autoantibodies, such as anti-glutamic acid decarboxylase (anti-GAD65) antibodies, is the most specific test to confirm an autoimmune etiology and differentiate type 1 from type 2 diabetes. Serum insulin or C-peptide levels can also be helpful but may be equivocal at presentation. A lipid panel and urine microalbumin are important for assessing complications but do not establish the underlying diagnosis.

Question 14

1. Reassure him that screening is not needed until age 55
2. Recommend lifestyle modifications and re-evaluate in one year
3. Perform screening with a hemoglobin A1c test (correct answer)
4. Start empiric low-dose metformin for prevention

Explanation: Current guidelines from the American Diabetes Association recommend screening for type 2 diabetes in all adults beginning at age 35. Screening is also recommended for asymptomatic adults of any age who are overweight or obese (BMI ≥25 kg/m² or ≥23 kg/m² in Asian Americans) and have one or more additional risk factors. This patient is 47, is obese (BMI 32), and has two risk factors (hypertension and a first-degree relative with diabetes). Therefore, screening is indicated. Any of the standard tests (HbA1c, fasting plasma glucose, or 2-hour OGTT) are appropriate. Reassurance or delaying screening would be incorrect. Metformin is considered for prevention only in those with diagnosed prediabetes, not for primary screening.

Question 15

1. A subcutaneous basal-bolus regimen
2. A subcutaneous sliding-scale insulin regimen
3. A continuous intravenous insulin infusion (correct answer)
4. Withholding insulin until glucose is >400 mg/dL

Explanation: For critically ill patients, especially those in shock or on vasopressors, a continuous intravenous insulin infusion is the preferred method for glycemic control. This method allows for precise and rapid titration of insulin delivery to maintain blood glucose levels within a target range (typically 140-180 mg/dL), which has been shown to improve outcomes. Subcutaneous insulin absorption can be erratic in patients with peripheral edema and poor perfusion, making basal-bolus or sliding-scale regimens less reliable and potentially dangerous in the ICU setting. Withholding insulin is inappropriate as severe hyperglycemia is associated with poor outcomes in critical illness.

Question 16

1. Glipizide
2. Sitagliptin
3. Pioglitazone
4. Liraglutide (correct answer)

Explanation: For patients with type 2 diabetes and established atherosclerotic cardiovascular disease (ASCVD), such as this patient with a prior myocardial infarction, guidelines recommend adding an agent with proven cardiovascular benefit. Glucagon-like peptide-1 (GLP-1) receptor agonists (e.g., liraglutide, semaglutide) and sodium-glucose cotransporter-2 (SGLT2) inhibitors (e.g., empagliflozin, canagliflozin) have demonstrated a reduction in major adverse cardiovascular events. Liraglutide is a GLP-1 receptor agonist and is an excellent choice. Glipizide (a sulfonylurea) and sitagliptin (a DPP-4 inhibitor) are glucose-lowering but are considered cardiovascularly neutral. Pioglitazone is associated with a risk of heart failure exacerbation and weight gain and would not be ideal in this patient.

Question 17

1. Repeat fasting plasma glucose on a different day (correct answer)
2. Oral glucose tolerance test
3. Serum C-peptide level
4. Glutamic acid decarboxylase antibody test

Explanation: The diagnosis of diabetes mellitus can be made with two abnormal results from the same sample or, more commonly, with two abnormal results on separate days. This patient has one abnormal fasting plasma glucose (FPG ≥ 126 mg/dL). A repeat FPG on a different day is the most straightforward and recommended approach to confirm the diagnosis. An oral glucose tolerance test is another valid diagnostic test but is less convenient than a repeat FPG. C-peptide and GAD antibodies are used to differentiate between type 1 and type 2 diabetes after a diagnosis is established, not for initial diagnosis.

Question 18

1. Twice-daily injections of NPH and regular insulin
2. Once-daily injection of insulin glargine
3. Basal-bolus therapy with insulin detemir and insulin aspart (correct answer)
4. Sliding-scale regular insulin based on pre-meal glucose readings

Explanation: A basal-bolus regimen, consisting of a long-acting basal insulin (like detemir or glargine) once or twice daily and a rapid-acting bolus insulin (like aspart or lispro) with meals, is the most physiologic approach and allows for the greatest flexibility. This regimen allows the patient to adjust the mealtime insulin dose based on carbohydrate intake ('carb counting') and correct for high blood glucose levels. A twice-daily mixed insulin regimen (NPH/regular) is less flexible and requires a more rigid meal schedule. Basal insulin alone is insufficient for type 1 diabetes. Sliding-scale insulin alone is not an effective long-term management strategy.

Question 19

1. Aggressive intravenous fluid resuscitation with 0.9% saline (correct answer)
2. Intravenous regular insulin bolus followed by an infusion
3. Intravenous sodium bicarbonate administration
4. Empiric broad-spectrum antibiotics

Explanation: This patient's presentation with profound hyperglycemia, hyperosmolality, altered mental status, and minimal acidosis is characteristic of Hyperosmolar Hyperglycemic State (HHS). The most critical initial intervention in HHS is aggressive intravenous fluid resuscitation to correct the severe dehydration and hyperosmolarity, which are the primary drivers of morbidity. Patients with HHS have a profound fluid deficit, often 8-12 liters. While insulin is necessary, fluid replacement is the first priority and will also help lower blood glucose by improving renal perfusion and glucose clearance. Sodium bicarbonate is not indicated as there is no significant acidosis. Antibiotics are important for the underlying infection but are secondary to hemodynamic stabilization with fluids.

Question 20

1. Decrease the insulin infusion rate by half
2. Switch from 0.9% saline to 0.45% saline
3. Add dextrose to the intravenous fluids (correct answer)
4. Transition to subcutaneous basal insulin

Explanation: In the management of DKA, the goals are to correct dehydration, hyperglycemia, and acidosis, and to close the anion gap. This patient's glucose has improved to 210 mg/dL, but her anion gap remains elevated (normal <12 mEq/L) and bicarbonate is low, indicating that the ketoacidosis has not yet resolved. The insulin infusion must be continued until the anion gap closes. To prevent hypoglycemia while continuing the insulin infusion, dextrose (typically 5%) should be added to the intravenous fluids once the serum glucose falls to approximately 200-250 mg/dL. Decreasing the insulin infusion would slow the resolution of ketosis. Transitioning to subcutaneous insulin is only appropriate after the anion gap has closed and the patient can tolerate oral intake.