DIETARY-SODIUM RESTRICTION IMPAIRS INSULIN SENSITIVITY IN NONINSULIN-DEPENDENT DIABETES-MELLITUS

Dietary sodium restriction has a variety of effects on metabolism, inc luding activation of the renin-angiotensin system. Angiotensin II has complex metabolic and cardiovascular effects, and these may be relevan t to the effects of both nonpharmacological and pharmacological interv entions in noninsulin-dependent diabetes mellitus (NIDDM). We have ass essed the effect of dietary sodium restriction on insulin sensitivity and endogenous glucose production in eight normotensive patients with diet-controlled NIDDM who underwent hyperinsulinemic clamp studies in a randomized, double-blind, placebo-controlled cross-over protocol aft er two 4-day periods on sodium replete (160 mmol/day) and sodium deple te (40 mmol/day) diets. Mean +/- SD 24-h urinary sodium was 197 +/- 76 .0 mmol (replete) and 67 +/- 19.5 mmol (deplete), P = 0.03. Insulin se nsitivity was 42.0 +/- 11.3 mu mol/kg.min (replete) and 37.0 +/- 11.6 mu mol/kg.min (deplete), P = 0.04 (a reduction of 12%). Blood pressure was 130 +/- 21/78 +/- 11 mmHg (replete) and 128 +/- 12/73 +/- 10 mmHg (deplete). Dietary sodium restriction may result in a decrease in per ipheral insulin sensitivity in normotensive patients with NIDDM, possi bly via an elevation in prevailing angiotensin II concentrations.