How About Post-Meal Insulin?
Is there ever a time when you take insulin after your meals? Name Withheld
Janis McWilliams, RN, MSN, CDE, BC-ADM, responds: For the most part, rapid-acting insulin is administered before meals. Although it may be tempting to treat random high glucoses with some extra rapid-acting insulin at various times unrelated to meals, you should do this only if so advised by your doctor or diabetes educator. The effects of insulin can "stack," and too much insulin can result in hypoglycemia (low blood glucose).
There are exceptions. To explain, it helps first to review the different types of insulin. Basal insulins are long-acting insulins that ensure that your blood glucose remains controlled when you are not eating during the day or sleeping. Rapid-acting insulins are faster acting and are taken to cover mealtime spikes in glucose. The use of a basal/mealtime schedule is meant to best mimic the function of a normal pancreas. Mealtime insulin can be delivered by either an injection or an insulin pump. Basal insulin is given only via injections. (With a pump, a continuous infusion of fast-acting insulin serves as the "basal" function.)
Basal insulins include long-acting insulin detemir (Levemir) and insulin glargine (Lantus). Basal insulins are taken at the same time every day, and Levemir and Lantus are often used at bedtime and may need to be taken more than once daily. Intermediate-acting NPH insulin (Humulin N, Novolin N, and ReliOn N) can also be given at bedtime, or in combination with a rapid-acting insulin before meals.
Rapid-acting insulins include insulin lispro (Humalog), insulin aspart (NovoLog), and insulin glulisine (Apidra). Regular insulin (Humulin R, Novolin R, and ReliOn Regular), a short-acting insulin, works best when given about 30 minutes before meals. Other rapid-acting insulins are usually given immediately before the meal.
That said, special circumstances may dictate that insulin be taken post-meal. For example, parents of toddlers or very young children often do not administer the rapid-acting insulin until they see how much (and how many carbs) the child has eaten. And adults who have problems with delayed food absorption (as in gastroparesis), suppressed appetite, or other issues may delay their insulin injection based on recommendations of their health care provider.