When is hypoglycemia most likely to occur with regular insulin?

Hypoglycemia is most likely to occur with regular insulin when the peak action of the insulin coincides with periods of fasting or inadequate food intake. Regular insulin typically has its onset within 30 minutes, peaks approximately 2 to 3 hours after administration, and lasts for about 6 to 8 hours.

If a person takes regular insulin before lunch, the peak action of the insulin would occur right around lunchtime or shortly before, particularly if they have not eaten enough. This peak can lead to a drop in blood sugar levels, resulting in hypoglycemia if the glucose intake does not match the insulin's activity.

In contrast, for meals like breakfast, dinner, or after lunch, the timing of regular insulin's peak may either align with the intake of food or could be mitigated by eating, thus reducing the likelihood of hypoglycemia at those times. Therefore, taking insulin before lunch represents the most critical period for potential hypoglycemia if adequate carbohydrates are not consumed promptly.