Insulin resistance in offspring of hypertensive parents

Abstract

Objective - To determine if insulin resistance is present in normotensive adults at increased risk of developing hypertension. Design - Normotensive subjects with at least one hypertensive parent were paired with offspring of normotensive parents (controls), being matched for age, sex, social class, and physical activity. Setting - Outpatient clinic. Subjects - 30 paired subjects (16 men and 14 women) with and without a family history of hypertension, aged 18-32, with a body mass index <25 kg/m2, with blood pressure <130/85 mm Hg, and not taking drugs. Interventions - Euglycaemic glucose clamp (two hour infusion of insulin 1 mU/kg/min) and intravenous glucose tolerance test (injection of 100 ml 20% glucose). Main outcome measures - Insulin mediated glucose disposal and insulin secretion. Results - The offspring of hypertensive parents had slightly higher blood pressure than did the controls (mean 117 (SD 6) υ 108 (5) mm Hg systolic, p=0·013; 76 (7) υ 67 (6) mm Hg diastolic, p=0·017). Their insulin mediated glucose disposal was lower than that of controls (29·5 (6·5) υ 40·1 (8·6) μmol/kg/min, p=0·002), but, after adjustment for blood pressure, the difference was not significant (difference 6·9 (95% confidence interval -1·5 to 15·3), P=0·10). Insulin secretion in the first hour after injection of glucose was slightly but not significantly higher in the offspring of hypertensive patients (9320 (5484) υ 6723 (3751) pmol.min/l). The two groups had similar concentrations of plasma glucose (5·2 (0·3) υ 5·1 (0·4) mmol/l), serum cholesterol (4·4 (0·8) υ 4·6 (0·8) mmol/l), serum triglyceride (0·89 (0·52) υ 0·68 (0·27) mmol/l), and serum low density lipoprotein cholesterol (2·81 (0·65) υ 2·79 (0·61) mmol/l). The offspring of hypertensive parents, however, had lower serum concentrations of high density lipoprotein cholesterol (1·24 (0·31) υ 1·56 (0·35) mmol/l, p=0·002) and higher serum concentrations of non-esterified fatty acids (0·7 (0·4) υ 0·4 (0·4) mmol/l, p=0·039). Conclusions - Young normotensive subjects who are at increased risk of developing hypertension are insulin resistant.