Illustrative cases of intensive insulin therapy in special situations
- David K McCulloch, MD
David K McCulloch, MD
- Clinical Professor of Medicine
- University of Washington
Diabetic patients who are motivated and well educated can often keep their blood glucose concentrations in the normal or near-normal range on routine days. They may, however, need advice for more unusual events. Although it is not possible to cover all eventualities, some general guidelines can be given.
Maintenance of strict glycemic control with intensive insulin therapy is facilitated by relative consistency in the quantity and timing of carbohydrate intake. These may be difficult to anticipate when going to a restaurant or eating at a friend's house. It is helpful to keep a carbohydrate supply on hand, to check blood glucose frequently, and to learn to estimate (visually or by asking the chef) the carbohydrate content in the meal.
Case 1 — A 41-year-old man, whose diabetes is usually well controlled (glycated hemoglobin [A1C] of 5.5 percent), takes 8 units of regular and 18 units of NPH before breakfast , 4 units of regular before lunch, 8 units of regular before his evening meal, and 10 units of NPH before bedtime. One evening, after a busy day at work, he is invited to dinner with friends. Dinner will not be served until about 8:30 PM, although he usually eats his evening meal at about 5:45 PM. His blood glucose values for that day were 106 mg/dL (5.9 mmol/L) before breakfast, 112 mg/dL (6.2 mmol/L) before lunch, and 68 mg/dL (3.8 mmol/L) at 5:30 PM.
Because of the relatively low blood glucose values, he eats a snack, ingesting the same amount of food as his usual bedtime snack (30 g). At 8:15 PM, after arriving at the party, his blood glucose is 137 mg/dL (7.6 mmol/L). This seems to be a reasonable value and he decides to take his usual pre-evening meal dose of insulin (8 units of regular). When he gets home at 11 PM, having eaten more than usual, his blood glucose is 362 mg/dL (20.1 mmol/L). He wonders what to do now.
Interpretation — The patient has done quite well so far. He should take his usual dose of NPH (10 units) plus an extra dose of regular (perhaps 4 units) to correct the hyperglycemia. With the advantage of hindsight, he should have taken more than his usual dose of regular insulin before the meal or eaten less. Depending upon how well he knew the hosts, he might have asked what was going to be served so that he could have made a better guess as to the appropriate insulin dose. If the patient is taught detailed carbohydrate counting, including carbohydrate-to-insulin ratios, his ability to estimate how much extra regular insulin to take would improve. The use of insulin pens and rapid-acting analogs (such as lispro insulin, insulin aspart, or insulin glulisine) have made eating out more convenient. Although not recommended for usual care, when necessary it is possible to take the rapid-acting analog immediately after finishing the meal, basing the dose on the pre-meal blood glucose level plus the amount of carbohydrate that has been eaten.