Effect of diet restriction on 24-hr urinary C-peptide excretion in non-insulin-dependent non-obese diabetic subjects.

Changes in insulin secretory responses by diet restriction were analyzed in non-insulin-dependent non-obese diabetic subjects (NIDDM-NO) as well as in healthy volunteers by determining 24-hr urinary C-peptide immunoreactivity (24-hr UCPR). Insulin sensitivity for glucose utilization was measured by using cyclic somatostatin. Overnight fasting plasma glucose concentrations decreased in NIDDM-NO; however, 24-hr UCPR was reduced in both NIDDM-NO and healthy controls by diet restriction (25 kcal/kg) for 14 days. The level of 24-hr UCPR was higher but insulin sensitivity was lower in NIDDM-NO as compared with those in healthy controls. Therefore, diet restriction may be effective in controlling hyperglycemia and hypersecretion of insulin in NIDDM-NO, but it alone may not improve the reduced insulin sensitivity.