Insulin versus glipizide treatment in patients with non-insulin-dependent diabetes mellitus: Effects on blood pressure and glucose tolerance

Insulin resistance that exists in patients with essential hypertension and in those with non-insulin-dependent diabetes mellitus (NIDDM) may be the common denominator for the impaired glucose homeostasis and elevated blood pressure (BP) levels in patients with NIDDM. Therefore, treatment that improves insulin action may also improve BP levels. Consequently, a four-phase (glipizide υ insulin) cross-over design study was conducted to determine a better effect of glipizide treatment on insulin sensitivity and the effect this has on BP in 19 NIDDM patients. Patients were subjected to 1 month of diet only (phase I) followed by 3 months of glipizide treatment (phase II), then an additional 1 month of diet only (phase III), and finally 3 months of insulin treatment (phase IV). At the end of phases I, II, and IV oral glucose tolerance tests (OGTT) were performed and plasma glucose, insulin, and C-peptide levels were analyzed. Fasting plasma glucose, insulin, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides, glycated hemoglobin, fructosamine, and 2-h postprandial plasma glucose were also analyzed at each phase. Supine and sitting BP levels and body weights were determined biweekly during the study. With the exception of higher plasma insulin and C-peptide levels during the OGTT (area under the curve) in phase IV (insulin) υ phase II (glipizide) (both P< .05), and higher fasting plasma insulin levels (P< .06), there were no consistently significant metabolic differences between phases IV and II. Plasma glucose levels, fasting and during the OGTT, were similar in the two phases and there were no significant differences between phases IV and II in BP levels, body weights, and lipid metabolism measures. Thus, compared with insulin, glipizide treatment in patients with NIDDM is associated with better insulin sensitivity and with lower insulinemia, but these improvements are not associated with improvements in BP control.