Change to U-100 insulin does not appear to affect insulin absorption.

Change to U-100 insulin does not appear to affect insulin absorption On 1 March a two year programme began in the United Kingdom of phased transfer of all diabetics requiring insulin to insulin in a strength of 100 units/ml. Factors affecting the absorption of insulin from subcutaneous tissues include site of injection,' exercise,2 dose,3 strength of the insulin, volume, and the patient's age.4 We examined the effect of giving identical doses of soluble insulin in strengths of U-40 (40 units/ml) and U-100 (100 units/ml). Eight diabetic children aged 7-15 years were given on two successive mornings in hospital exactly comparable subcutaneous injections into the thigh of either U-40 or U-100 neutral insulin (Actrapid MC) followed by identical breakfasts and exercise. The previous evening they had received their normal dose of a combination of soluble and intermediate acting insulins. To avoid rapid hypoglycaemia the dose of insulin given was roughly two thirds of the usual total morning dose, the longer acting insulin being omitted. In four cases U-40 was given on the first morning followed by U-100 on the second morning, and in the other four cases the order was reversed. Blood glucose was measured half hourly for up to four hours after breakfast and the serum insulin concentration estimated on three occasions in each child. Samples were taken through an indwelling butterfly needle to avoid repeated venepuncture. Approval of the ethical committee was obtained. Two patients were excluded from the study because of practical difficulties. Free insulin concentrations rose from a mean basal value of 30-5±SD 23-4 mU/l in the subjects given U-40 insulin to a peak at 90 minutes of 58-8A28-3 mU/l. Patients' response to the same dose of U-100 insulin was a rise from a mean of 22-3 14-4 mU/l to 49 0± 1641 mU/l. Thus the increment in free insulin values was a mean of 28-3± 14-0 mU/l after U-40 insulin and 26-7_-24-0 mU/l after U-100 insulin. The closely similar increments in free insulin concentrations after injections of U-40 and U-l00 were reflected in the parallel rise and fall of the blood glucose concentrations (figure). The figure was constructed from the mean blood glucose values of six patients at specific times after the insulin injections. Thus the concentrations rose from a mean of 8-1 mmol/l (146 mg/100 ml) to a peak of 14 6 mmol/l (263 mg/100 ml) at 90 minutes after U-40 insulin. The comparative figures …