My son takes 36 units of NPH with 4 units of Regular and 6 units of Humalog in the morning, he eats 3 carbs for breakfast (which is fairly consistent), and two hours after his meal, his sugar can be anywhere from 150 – 350 mg/dl [mmol/L]. We have increased his morning Humalog from 3 to the current 6 units, but the variability still continues. Our apprehension now is that he could be rebounding. Can a rebound happen within one to two hours of a full meal?

One would not expect “rebound hyperglycemia” after just one to two hours after a meal. The more likely explanations would include an incomplete, albeit consistent, miscalculation of carbs, inconsistent activity after the meal, and some others.

Remember that NPH begins to work about two hours after the dose (and “peaks” about six to eight hours later), Regular begins to work about 30 minutes after a dose (and peaks two to three hours later), and Humalog begins to work generally in less than 15 minutes (and peaks about 90 minutes later). It also may be a good time to calculate the Humalog based on carbohydrate counting. Your regular doctor can advise you, if you are not doing this already.

DS