Diabetes, Vol 29, Issue 1 78-80, Copyright © 1980 by American Diabetes Association
Overnight basal insulin requirements in fasting insulin-dependent diabetics
WL Clarke, MW Haymond and JV Santiago
Overnight basal insulin requirements to maintain eugycemia were determined
in six insulin-requiring diabetic subjects using a feedback-controlled
(closed loop) insulin infusion system. Mean hourly insulin infusion rates,
required to maintain plasma glucose concentrations at approximately 100
mg/dl, were remarkably stable from 2400 h to 0600 h; however, a twofold to
threefold increase in insulin requirements was observed in each subject
between 0600 h and 0900 h. This increase in amount of basal insulin
required was not associated with increases in plasma glucagon or growth
hormone concentrations, but occurred simultaneously with normal diurnal
increases in plasma cortisol. These findings suggest that normal diurnal
increases in plasma cortisol, independent of the content of the morning
meal, contribute to the increased amount of morning insulin required in
diabetic subjects. Programs designed for optimal open loop insulin delivery
may benefit from modifications designed to coincide with this increase in
amount of basal insulin required in the early morning.