Role of Risk Factors in Complications of Diabetes Mellitus1

To compare antecedent and concurrent factors in diabetics and matched controls, and to measure the role played by these factors in mortality, 371 “diabetics” aged 20–75 years were identified from a source population of 26, 000 participants in a community-wide health survey carried out in Washington County, Maryland, in 1974. (“Diabetics” were those who reported on the survey questionnaire that they had taken antidiabetic medications in the previous 48 hours.) Two sex- and age-matched controls for each diabetic were selected from the survey population. Comparison characteristics included blood pressure measured at the time of the survey, marital status, grades of school completed, cigar, cigarette, and pipe smoking, use of aspirin, oral contraceptives, female hormones and treatment for hypertension. Deaths were ascertained prospectively for 39 months following the 1974 survey. Diabetics had higher systolic blood pressures (SBPs) than controls, the distribution for diabetics resembling that of controls who were ten years older. More diabetics reported treatment for hypertension, and diabetics under treatment for hypertension had higher SBPs than treated controls. Both male and female diabetics treated with insulin or oral agents alone showed similar patterns, with orally treated females showing the largest differences between cases and controls. Orally treated females had over twice the rates of SBP over 160 mmHg or of reported treatment for hypertension than did controls. It was also found that controls had completed more years of school, reported more use of oral contraceptives and female hormones, and used more aspirin than diabetics. Diabetics were more likely to have been married. Smoking habits did not differ between diabetics and controls except for more cigar smoking among diabetics. Diabetics had significantly higher mortality rates than controls in the 39 months after the survey. For all causes of death, diabetic rates were 2.5 times control rates. The increase was 1.5 times for orally treated and eight times for insulin-treated diabetics compared with their own controls. For vascular causes, the mortality risk for diabetics was increased 4.8 times overall, 2.5 times for the orally-treated, and 14.2 times for the insulin-treated compared with their own controls.