Effect of prolonged optimal blood sugar control by i.v. insulin administration on plasma free fatty acid and glycerol concentrations of insulin-dependent diabetics during exercise

Four type I diabetics were kept close to normoglycemic during a period of 1 month by means of a an open loop i.v. insulin infusion system (Siemens). During submaximal physical exercise their metabolic response was nearly normal. No hypoglycemic episodes during exercise were registered despite the fact that the regular basal infusion rate was not changed. The level of free fatty acids rose approximately to the same extent as in normal subjects. A slight inhibition of lipolysis during i.v. insulin therapy was apparent from the less marked rise of the glycerol levels. The feasibility of a simple open loop i.v. insulin regimen over a prolonged period of time is underscored by these results which show that the basal insulin infusion rate can be kept constant during exercise.