In a patient on insulin who skipped a meal, within which window is hypoglycemia most likely to occur?

• A. 1-2 hours after dose
• B. 2-4 hours after dose
• C. 4-6 hours after dose
• D. 8-12 hours after dose

Answer: (C)

When insulin is in play, it lowers blood glucose by helping cells take up sugar and by reducing liver glucose output. If a meal is skipped, there isn’t the incoming glucose to balance that insulin action, so the risk of hypoglycemia rises at the time insulin is most active.

For many common insulin regimens, the intermediate-acting insulin has its peak effect a few hours after injection, typically around four to six hours. That’s when the glucose-lowering action is strongest while there’s no carbohydrate being consumed to raise blood glucose, making hypoglycemia most likely in this window.

If instead a rapid-acting insulin were used, the peak would occur earlier (about one to two hours), and with a long-acting basal insulin there isn’t a sharp peak but a more constant action; the four-to-six hour window is the period of highest risk for the insulin type that peaks then and no meal is available to offset it.