We evaluated the course of total parenteral nutrition (TPN) therapy in patients with hyperglycaemia. We studied 1) incidence of hyperglycaemia, 2) amount of glucose and insulin provided and 3) incidence of metabolic problems in patients receiving TPN who required insulin to attain metabolic control. The group included 91 patients, 38 women (64 +/- 15 years) and 53 men (64 +/- 12 years), who developed glycaemia higher than 200 mg/dl. Nine patients had a previous diagnosis of IDDM, 36 NIDDM and 46 secondary hyperglycaemia.. Total caloric requirements were initially supplied at 132 +/- 20% the basal energy expenditure (Harris-Benedict formula), and 1.4 +/- 0.3 g/kg of amino-acids. Initially, TPN provided 150-200 g/day of glucose (2.1 mg/kg/min). Regular insulin was added to the bag. The annual incidence of hyperglycaemia was estimated to be 121 per 1000 patients. Mean insulin requirements were 50 U/day (25 to 150 U/day), 0.7 +/- 0.3 U/kg. Comparing with prehospitalization insulin dose, 22% needed similar doses, and 11% lower doses. IDDM patients needed 1.7 times their pre-admission dose (1-4.5 times). The ratio of insulin:glucose in TPN was 0.3 +/- 0.1 U/g (0.1-1.2 U/g). Patients with renal failure had similar insulin requirements (56 +/- 26 U/day) than patients with normal renal function (49 +/- 19 U/day). None of the patients developed glycemic complications. In conclusion, diabetic patients receiving TPN have an acceptable metabolic control if individualized prescriptions and supplemental insulin are used.