Insulin resistance, exercise capacity and body composition in subjects with two hypertensive parents

Objective To study insulin resistance in subjects with strong genetic predi sposition to essential hypertension compared with non-disposed subjects. Subjects Thirty normotensive subjects aged 18-35 years whose parents both h ad essential hypertension, and 30 age- and sex matched subjects whose paren ts were both normotensive, were studied. Subjects or parents with diabetes and morbid obesity were excluded. Methods The study comprised (1) a frequent sampling oral glucose tolerance test; (2) an isoglycemic hyperinsulinemic clamp study; (3) an analysis of b ody composition by dual-energy X-ray absorptiometry; (4) an exercise test w ith gas exchange analysis; and (5) investigation of composition of usual di et by diet registration for 5 days. Results The 24-h diastolic blood pressure was higher in subjects predispose d to hypertension compared with the controls: 78.1 versus 74.0 mmHg (confid ence interval for the difference between the means; -0.5; -7.9), but the in sulin sensitivity index was similar: 312 versus 362 I-2 min(-1) pmol(-1) kg (-1) (28; -129), The two groups were similar in terms of body composition, exercise capacity and composition of usual diet. Resting and 24-h diastolic blood pressures were correlated to abdominal fat mass but not to insulin s ensitivity. Conclusion Subjects with a strong genetic predisposition to essential hyper tension had increased diastolic blood pressure compared with subjects with normotensive parents, but they were not insulin resistant. This may be due to the subjects being highly selected as to confounding factors. The increa sed blood pressure in the hypertension prone subjects could not be attribut ed to differences in body composition, exercise capacity or dietary habits. J Hypertens 1999, 17:1273-1280 (C) Lippincott Williams & Wilkins.