Blood pressure in children, adolescents and young adults with type 1 (insulin-dependent) diabetes.

Blood pressure has been measured by a single observer using a standardised technique in 163 Type 1 (insulin-dependent) diabetic patients aged 4 to 32 years, 232 of their non-diabetic siblings in the same age range and in 292 of their natural parents. Results for each sex were examined separately by analysis of variance. Systolic pressures were not significantly different overall nor in any single 4-year age band. In contrast, phase IV diastolic pressure was slightly but significantly higher in the diabetic males than in their sibling group overall (increment = +2.8 mmHg; p less than 0.03), a difference also shown individually within the 16-20 year age band (81.3 versus 76.5 mmHg, p less than 0.025). There were no significant differences in diastolic pressure between the female groups, and no effect of duration of diabetes on blood pressure was shown in either sex. Eighteen of 97 male diabetic patients (19%) had mean blood pressures above the 90th centile for age, derived from the sibling data, compared with 12 of 137 siblings (9%, p = 0.05). The higher blood pressures among the diabetic males could not be explained solely by early nephropathy; familial factors appeared to be important in the determination of elevated blood pressure in this group as well as in the siblings. Alone, these small differences in blood pressure are unlikely to make a major contribution to the incidence of diabetic vascular disease, but the isolated increase in diastolic pressure may indicate altered vascular regulation in Type 1 diabetes.