Insulin resistance and urinary excretion of sodium in hypertensive patients with non-insulin dependent diabetes mellitus.

BACKGROUND: Hyperinsulinemia has been implicated in the pathogenesis of hypertension both in non-diabetic and diabetic patients. A causal relationship between renal sodium retention and hyperinsulinemia is speculated to play role in the development of hypertension in diabetes mellitus.
MATERIAL AND METHODS: Twenty patients (12 males; 8 females) with hypertension and non-insulin dependent diabetes mellitus (NIDDM) and twenty normotensive patients (11 males, 9 females) with NIDDM were included in the present study. Blood samples for glucose and immunoreactive insulin (IRI) assay were collected at 0, 30, 60 and 120 minutes after 75 g of glucose per oral. Urinary sodium excretion in 24 hrs was estimated by flame photometry. Insulin response to glucose and correlation between basal insulin secretion and urinary sodium excretion were evaluated.
RESULTS: Mean fasting plasma glucose value was significantly raised in hypertensive group in comparison with normotensive group of diabetic patients. Patients with diabetes and hypertension and significantly higher level of serum IRI than normotensive patients with diabetes mellitus. Urinary sodium excretion was significantly lower in diabetic patients with hypertension than in diabetic patients without hypertension. A negative correlation between basal insulin level and urinary Na+ excretion was observed in hypertensive patients with NIDDM.
CONCLUSION: A negative correlation between hyperinsulinemia and 24 hrs urinary Na+ excretion was observed in patients with diabetes and hypertension. The study highlights that patients with diabetes mellitus have tendency to retain sodium under the influence of insulin but this needs further evaluation.