INSULIN-RESISTANCE IS COUPLED TO LOW PHYSICAL-FITNESS IN NORMOTENSIVEMEN WITH A FAMILY HISTORY OF HYPERTENSION

Objective: To investigate insulin sensitivity and the influence of lev el of physical fitness in men with a family history of hypertension an d in control subjects. Design: Insulin sensitivity was determined and physical fitness estimated in 39 normotensive, glucose-tolerant men wi th a family history of hypertension (Relatives group) and in 29 age- a nd body mass index-matched normotensive men with no such family histor y (Controls group). Methods: The euglycaemic hyperinsulinaemic clamp t echnique (steady-state insulin concentration approximately 100mU/l) wa s used to determine insulin sensitivity. Physical fitness, measured as maximal oxygen uptake, was estimated from the heart rate response to a submaximal exercise test. Results: Insulin sensitivity index and est imated maximal oxygen uptake were lower in the Relatives than in the C ontrols. There was a positive correlation between insulin sensitivity and maximal oxygen uptake in both groups. In the Controls there was a negative correlation between insulin sensitivity and waist:hip ratio, but this relationship was not found in the Relatives. Conclusions: The present findings indicate that reduction of insulin sensitivity prece des the development of high blood pressure and may be coupled to low p hysical fitness. As abdominal fat distribution seems not to be related to insulin sensitivity in subjects with a family history of hypertens ion, changes in muscle fibre composition or muscle glucose metabolism, or both, might explain the lower insulin sensitivity and physical fit ness in the Relatives.