Pumped intravenous insulin in experimental diabetes

We infused experimentally diabetic animals continuously with exogenous insulin for periods of up to 324 days. Direct intravenous infusions from a prototype of an implantable device were used to explore whether this route can achieve repetitive control of fasting glycaemia within normal limits, here defined as being between 60 and 120 mg/dl. Fasting plasma glucose levels were controlled by simply adjusting the rate of exogenous insulin delivery when the observed level was outside the range of 100-120 mg/dl. An analysis of the results obtained indicated that 73% (427/591) of the fasting plasma glucose levels were within these normal limits. Remarkably, only 1% (6/591) of them were below 60 mg/dl, the lowest being 42 mg/dl. Hyperglycaemia above 150 mg/dl was seen in 11% (67/591) of the observations. However, all (6/6) of the hypoglycaemic episodes and most, 87% (58/67), of the hyperglycaemic episodes were of an accountable nature secondary to mechanical failures, electrical failures, methodologic or other problems encountered episodically during the long course of these studies. Two parallel control groups of experimentally diabetic animals received the same diet and were treated prospectively by daily subcutaneous injections for periods up to 224 days. The goal of this treatment was to attain metabolic control by either "conventional" or "intensified" injection methods. To these ends, fasting plasma glucose levels were measured on a daily basis (5 days/week) in both groups, and also at intervals postprandially in the intensively controlled group. These data were used to adjust insulin dosages. An analysis of the results indicated that only 24% (148/617) of the fasting plasma glucose levels were within the normal limits.(ABSTRACT TRUNCATED AT 250 WORDS)