Arterial pressure in clinically apparent diabetics

Abstract

The relationship between arterial blood pressure and clinically apparent diabetes mellitus was examined by measuring blood pressure, under standardised conditions, in 735 ambulant diabetic patients attending St. Mary's and King's College Hospital, London. Other biometric, clinical and family data were also systematically collected. A large proportion of first degree relatives of the diabetics and a control group of first degree relatives of non-diabetics were also seen and examined; they were also tested for the presence of unsuspected diabetes. Blood pressure in diabetics was evaluated in two ways. Mean pressures (systolic and diastolic) were calculated by age and sex and compared with similar data from two British non-diabetic populations. In addition, age and sex adjusted blood pressure "scores" were derived for each of the diabetic propositi and for the relatives by calculating the degree to which their pressures deviated from the mean of a corresponding age/sex group of non-diabetics. These deviations were then made comparable by standardising them for the systematic change in variance with age and sex. Using both "raw pressures" and "adjusted scores" the influence of age, sex, obesity, arm girth, response to diagnosis and ethnic, obstetric and anamnestic features were examined. Analysis of the influence of various characteristics of the diabetic state on blood pressure was made; this included mode of presentation, known duration; insulin dose and degree of metabolic control. Finally the relationship of blood pressure levels to the long-term sequels of diabetes was analysed with special reference to renal disease, eye changes, neuropathy and arterial disease. No systematic difference between arterial blood pressure in diabetics and a suitable control population was detected. Younger patients, females more than males, tended to have somewhat higher mean diastolic pressures but these were balanced by rather lower mean pressures in older diabetics. There was evidence of raised pressure levels at the time of diagnosis of diabetes, particularly in older patients, which "settled" with time for reasons which were not clear. The relationship of arterial pressure with adiposity was comparable to that in non-diabetics. After allowance for age and sex, blood pressures and scores were not related to the mode of onset of the diabetes. In the youngest onset group, however, known duration of diabetes appeared to correlate positively with arterial pressure in excess of the effect of age. Insulin dose and metabolic characteristics of the diabetes showed little clear association with arterial pressure but, as expected, patients with evidence of renal disease had higher mean pressures. However, cause-effect relationship between raised pressure and renal disease in diabetics may operate in both directions. Some elements of retinopathy were positively correlated with blood pressure; others were not. The role of co-existing renal disease in determining this association was examined...