25.9 : Insulin: Dosing Regimen and Adverse Effects

Insulin-replacement therapy usually includes both long-acting insulin (basal) and short-acting insulin (to cater to postprandial needs). In a diverse group of type 1 diabetes patients, the average daily insulin dose is typically 0.5-0.7 units/kg body weight. However, obese patients and pubertal adolescents may need more due to insulin resistance.

The basal dose constitutes about 40%-50% of the total daily dose, with the rest as premeal insulin. The mealtime insulin dose should mirror anticipated carbohydrate intake and a supplemental scale of short-acting insulin can be added for blood glucose correction. Achieving euglycemia requires more complex regimens involving multiple injections of long- or short-acting insulin.

Therapeutic endpoints guide the insulin dose used, assisted by self-monitoring of glucose and A1c measurements. Postprandial injection of a short-acting analog, based on actual food consumption, may enable smoother glycemic control in patients with gastroparesis. Hypoglycemia, a significant risk, must be balanced against the benefits of normalizing glucose control. Insulin treatment is linked with modest weight gain and rare allergic reactions. Atrophy of subcutaneous fat at the injection site (lipoatrophy) was a side effect of older insulin preparations. At the same time, hypertrophic subcutaneous fat depot is attributed to the lipogenic action of insulin at repeated injection sites.