Limitations of diet therapy in patients with non-insulin-dependent diabetes mellitus.

Unlabelled: Sixty-one patients with non-insulin-dependent diabetes mellitus and fasting blood glucose of 12.0 +/- 0.6 mmol/l were studied before and after dietary treatment in an outpatient setting. At the start of the study 33 patients were obese (body mass index greater than 27.0 kg/m2). Twenty patients were newly diagnosed, median known duration of diabetes in the others was 5 years. Beta-cell function was measured by the release of C-peptide after i.v. injection of 1 mg glucagon (area under the curve of C-peptide = AUC-cp), as well as calculated according to the formulae of Matthews. Insulin action was estimated by measurement of fasting blood glucose, insulin and free fatty acids (FFA) concentrations. Non-obese patients showed more severe beta-cell deficiency than the obese ones (AUC-cp 2586 +/- 158 vs. 3294 +/- 277 pmol/l per 15 min), and did not improve in metabolic control during treatment. In the obese patients three response patterns to treatment were observed: weight loss and improvement in metabolic control accompanied primarily with increased beta-cell function or increased insulin action, or worsening of metabolic control. Those with less impaired beta-cell function and shorter known duration of diabetes showed the most favourable response.

In Conclusion: non-obese type 2 diabetes patients with fasting glucose levels above 10 mmol/l do not improve on dietary treatment alone; in obese type 2 diabetics weight reduction is essential and results in metabolic improvement, irrespective of the preceding fasting blood glucose concentrations. Improved beta-cell function as well as increased insulin action are responsible for this improvement.