Impaired glucose tolerance at five-year follow-up of young men with borderline hypertension.

BACKGROUND

Recent studies suggest that patients with essential hypertension have impaired glucose tolerance and are hyperinsulinemic compared with normotensive subjects. The aims of the study were (1) to follow blood pressures of 56 young men with borderline hypertension for 5 years, (2) to investigate glucose tolerance in these subjects, and (3) to determine the relation of insulin/glucose metabolism to structural vascular changes and hemodynamic patterns in borderline hypertension.

METHODS

Thirty-nine young (age 22-34 years) male subjects with borderline hypertension (SBP 140-160 and or DBP 85-95 mmHg initially) and 17 normotensive control subjects (SBP 110-130 and DBP 60-80 mmHg) participated in the study. Blood pressure was measured, a standard oral glucose tolerance test (OGTT) was performed, and glucose, insulin and C-peptide were determined before and 30, 60, 90 and 120 minutes after a standard 75-g glucose load. Post-ischemic forearm vasodilatory responses were examined by plethysmography.

RESULTS

At follow-up, the borderline hypertensives had maintained significantly higher blood pressures than control subjects. Borderline hypertensives also had significantly impaired glucose tolerance compared to control subjects. The insulin response had a somewhat more sluggish descent, but did not differ significantly from the response of normotensives. The C-peptide response pattern resembled that of insulin, but C-peptide was significantly elevated after 120 min. On the whole group level, there were only weak relations of insulin to blood pressure. By contrast, fasting insulin and post-load insulin levels were strongly correlated with body mass index, the waist-hip circumference ratio, triglyceride, and both total and LDL cholesterol. Across the whole group, there were significant correlations between forearm minimal vascular resistance and fasting insulin (r = +0.37 p = 0.007) and insulin area-under-the-curve (r = +0.28 p = 0.044). However, Rmin was even more strongly correlated with body mass index, suggesting that this relationship was related to degree of obesity.

CONCLUSION

Borderline hypertension in young men is a persistent condition which is associated with impaired glucose tolerance without hyperinsulinemia. This finding suggests that impaired glucose tolerance might be a more primary phenomenon in early hypertension devoid of lipid metabolic aberrations.