BASAL INSULIN-LEVEL OSCILLATIONS IN NORMOTENSIVE INDIVIDUALS WITH GENETIC PREDISPOSITION TO ESSENTIAL-HYPERTENSION EXHIBIT AN IRREGULAR PATTERN

Background Insulin is secreted in regular pulses at intervals of 12-14 min in normal fasting subjects. An abnormal pattern has been found in subjects with non-insulin-dependent diabetes mellitus (NIDDM) and in young individuals predisposed to NIDDM. It has been suggested that the re might be a causal relationship between insulin-secretion abnormalit ies and insulin resistance. Objective To examine whether insulin-secre tion abnormalities are also present in offspring of patients with esse ntial hypertension, Methods Eleven young (aged 18-35 years) normotensi ve individuals each of whom had two parents with essential hypertensio n were compared with 10 age- and sex-matched controls each of whom had two normotensive parents, We verified that diabetes and morbid obesit y were absent among the subjects and their parents, We studied basal i nsulin-secretion patterns during a 60 min period, glucose tolerance by administering an oral glucose-tolerance test, insulin resistance by u sing an isoglycaemic hyperinsulinaemic clamp and basal plasma catechol amine levels, Results Autocorrelation analysis of insulin concentratio ns showed that the hypertension-prone subjects had a significantly red uced or irregular oscillatory pattern compared with the regular insuli n-level oscillations with a period of 12-14 min in central subjects. T he hypertension-prone subjects had significantly higher systolic blood pressures and tended to be insulin-resistant Conclusion This is the f irst evidence of early insulin-secretion abnormalities in young normot ensive individuals with a genetic predisposition to essential hyperten sion, but with a normal glucose tolerance and without a genetic predis position to NIDDM. Early insulin-secretion abnormalities may be the ve ry first step towards the development of insulin resistance and an imp ortant factor initiating the hypertension in hypertension-prone indivi duals.