Hyperinsulinaemia and other metabolic disturbances in well-controlled hypertensive men and women: an epidemiological study of the Dalby population

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Abstract
Hypertensive subjects who have received no treatment have been found to be hyperinsulinaemic in previous studies using different populations. The present study was carried out to further examine the metabolic disturbances in carefully treated hypertensive subjects [diastolic blood pressure (DBP) < 90 mmHg] of both sexes from the Dalby population. Three hundred and ten subjects who had been hypertensive for more than 5 years [DBP 88.1 .+-. 0.5 (mean .+-. s.e.m.)] were compared with 288 normotensive controls, matched for sex and age and chosen from the same population. After an overnight fast and with no medication for 24 h, an oral glucose tolerance test was carried out. P-insulin and P-C-peptide were analysed and insulin sum (P-insulin at start + after 2 h of oral glucose tolerance test) and C-peptide sum were calculated. Insulin and C-peptide sums were higher (P < 0.001) in the hypertensive than in the normotensive subjects; 0.69 .+-. 0.03, 3.36 .+-. 0.08 and 0.41 .+-. 0.02, 2.74 .+-. 0.06, respectively. The diagnosis of hypertension, not the attained blood pressure level, correlated with insulin and C-peptide sums in multivariate analyses; F-values 20.96 (n = 598; P < 0.001) and 6.68 (P < 0.01), respectively. Hypertensive subjects under treatment, using calcium antagonists as monotherapy (n = 21), did not differ in age or body mass index from other hypertensives, but they had lower values for insulin and C-peptide sums; 0.45 .+-. 0.05 and 2.63 .+-. 0.18. Angiotensin converting enzyme inhibitors were not frequently used for monotherapy. In conclusion, hypertensives have hyperinsulinaemia and hyper-C-peptidaemia even though they have been carefully treated for several years. The diagnosis of hypertension, not the attained blood pressure level, seems to be of importance. The blood pressure of the hypertensives was reduced to meet current therapeutic goals, but did not reach normotensive levels. Calcium antagonists may have a favourable influence on the hyperinsulinaemia which merits further randomized, long-term studies.