Overnight basal insulin requirements in insulin dependent diabetics.

Programming open loop insulin delivery systems makes necessary the knowledge of patients insulin needs. It is frequently postulated that insulin needs increase at the end of the night in relation to the rise in cortisol secretion. According to this hypothesis is it justified to speed up the insulin infusion rate in the early morning? This question was addressed by studying insulin infusion rate by an artificial pancreas during the night in 12 C. peptide negative insulin dependent diabetics. They were connected to the artificial pancreas from 8 a.m. to 10 a.m. the next morning while on their habitual diabetic diet and slept as usual from 11 p.m. to 7 a.m. approximately. From 11 p.m. to 7 a.m. mean insulin infusion rate was 21.5 +/- 3.3 mU/Kg/h representing 15.6 +/- 1.6% of the dose delivered in 24 hours. Blood glucose was stable around 85 mg/dl. No significant differences were observed in the hourly insulin infusion rate during the night period, in spite of a slight tendency to a rise (from 21.1 +/- 2.8 to 22.1 +/- 2.6 mU/kg/h) tendency to a rise (from 21.1 +/- 2.8 to 22.1 +/- 2.6 mU/kg/h) after 4 a.m. On the basis of these results obtained in patients sleeping as usual it does not appear useful to envisage a systematic acceleration of insulin infusion rate by continuous delivery systems in the early morning.