Role of hyperglycemia and insulin resistance in determining sodium retention in non-insulin-dependent diabetes.

Sodium retention has been advocated to give rise to hypertension in humans. Increases in blood glucose and insulin concentrations ensue in the stimulation of sodium reabsorption by the kidney. Although the combined occurrence of hyperglycemia and hyperinsulinemia, frequently secondary to insulin resistance with regard to carbohydrate metabolism, is a hallmark of non-insulin dependent diabetes (NIDDM), the role of these abnormalities in determining an impaired natriuresis in NIDDM is not yet fully understood. We studied sodium homeostasis in 14 control subjects and 59 NIDDM normotensive, normoalbuminuric patients who were divided into two groups with markedly impaired (Group 2 NIDDM: 30) and less severely impaired (Group 1 NIDDM: 29) insulin sensitivity during euglycemic-hyperinsulinemic (80 to 90 microU/ml plasma insulin) clamp. A hyperglycemic (9 mmol/liter plasma glucose)--nearly euinsulinemic (20 to 40 microU/ml plasma insulin) clamp was also performed in the same 14 controls and in two cohorts of 22 Group 2 and 17 Group 1 NIDDM patients. The two groups of patients had similar overnight fasting glucose levels (Group 1 NIDDM vs. Group 2 NIDDM: 176 +/- 13 vs. 185 +/- 15 mg/dl, mean +/- SE). Conversely, overnight fasting plasma insulin was significantly higher in Group 2 NIDDM than in Group 1 NIDDM patients (Group 1 NIDDM vs. Group 2 NIDDM: 12 +/- 3 vs. 18 +/- 3 microU/ml, P < 0.05). Both NIDDM Groups had higher plasma glucose and insulin than controls (75 +/- 4 mg/dl and 6 +/- 3 microU/ml). Blood pressure levels and albumin excretion rates were slightly but significantly higher in Group 2 NIDDM, but not in Group 1 NIDDM patients, than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)