Aspects of insulin resistance in urbanisation-related hypertension in Zimbabwe: a preliminary report.

Insulin resistance has been associated with essential hypertension, obesity and old age. Likewise high blood pressure has been observed to develop in some rural people who migrate to urban areas in developing countries like Zimbabwe. The pathogenesis of this urbanisation-related hypertension is still unknown. We therefore investigated aspects of insulin resistance in urbanisation-related hypertension in Zimbabwean blacks using oral glucose tolerance tests. Thirty normotensive subjects and 30 newly diagnosed hypertensive patients participated in this study. All subjects had blood pressures measured by random zero sphygmomanometry. Fasting blood samples were taken before a 75 g oral glucose load was given. Four other blood samples were subsequently collected at 30 minute intervals and determination of blood glucose and insulin levels was made. Fasting glucose (mmol/l) and fasting insulin (in microU/ml) levels were, respectively, 4.8 +/- 0.2 and 19 +/- 2 in hypertensive patients which were significantly higher than 4.0 +/- 0.2 and 13 +/- 1.6 in normotensive patients (P < 0.05). In addition the area under the insulin curve was significantly higher in hypertensive than in normotensive patients (P < 0.05). These findings suggest that insulin resistance may play a role in urbanisation-related hypertension.