Influence of heat on insulin absorption: different effects on amorphous and soluble insulins.

A rise in ambient temperature stimulates the absorption of soluble, rapid-acting insulin. In the present study, the effect of intensive heat (Finnish sauna) on the absorption of amorphous insulin from a subcutaneous injection site in eight patients with type I diabetes was examined. The rate of absorption was determined by external measurement of the disappearance rate of 125I-labelled intermediate-acting (Semilente) insulin. The sauna (twice for 25 min at 85 degrees C) failed to stimulate insulin absorption significantly or to lower blood glucose levels as compared to a control day at 22 degrees C. Thus, heat has a different effect on the pharmacokinetics of amorphous and soluble insulins.