Effect of sulphonylurea administration on insulin secretion and amino acid metabolism in non-insulin-dependent diabetic patients.
Sulphonylureas lower blood glucose but other metabolic effects have been little studied. In an assessment of carbohydrate and amino acid metabolism in 9 patients with non-insulin-dependent diabetes mellitus (NIDDM) before and after 3 months' therapy with gliclazide, glycaemic control was improved (mean +/- S.D. glycosylated haemoglobin 13.8 +/- 1.9% before therapy, 10.2 +/- 2.1% after therapy (p less than 0.01], but fasting amino acid levels were not altered. In contrast, postprandial levels of branched chain amino acids (BCAA) were significantly reduced: total BCAA (valine, leucine, and isoleucine) 120 mins following a standard test meal fell from 717 +/- 71 mumol/l before therapy to 600 +/- 90 mumol/l after 3 months' therapy (p less than 0.01). This finding implies an increased action of endogenous insulin on skeletal muscle to promote uptake of BCAA postprandially and, in accord with this, peripheral insulin levels were significantly increased following drug treatment (peak insulin level 55.6 +/- 20.2 mU/l before therapy, 91.3 +/- 17.9 mU/l after therapy (p less than 0.01]. Sulphonylurea drugs therefore do not simply have a hypoglycaemic action but also affect amino acid metabolism in NIDDM patients.