SERUM ANTIOXIDANTS AND RISK OF NON-INSULIN-DEPENDENT DIABETES-MELLITUS

Objective: To examine whether serum levels of alpha-tocopherol, beta-c arotene and retinol were associated with risk of non-insulin dependent diabetes mellitus (NIDDM). Design and subjects: The study design was a nested case-control study within a longitudinal population study. Se rum levels of antioxidants were determined in 106 incident cases with non-insulin dependent diabetes mellitus detected on follow-up and 201 controls matched for sex, age and study region. Results: The incident cases had lower serum alpha-tocopherol and beta-carotene levels than c ontrols. The relative risk between the highest and lowest tertiles of serum alpha-tocopherol was 0.61 (95% confidence interval (CI) 0.32-1.1 5), between the highest and lowest tertiles of serum beta-carotene 0.4 5 (CI 0.22-0.92). Although the relative risk of highest compared with lowest tertile of serum alpha-tocopherol was not statistically signifi cant the inverse trend through the tertiles was (P < 0.05). The decrea sing risk of diabetes was particularly evident in the elderly, women, nonsmokers and the obese. However, adjustment for serum cholesterol, o besity, smoking and hypertension abolished the associations. The adjus ted relative risks in relation to serum a-tocopherol and beta-carotene (between highest and lowest tertiles) were 1.25 (CI 0.54-2.90) and 0. 93 (CI 0.3-2.32), respectively. No associations were observed relating to serum retinol. Conclusions: High levels of alpha-tocopherol and be ta-carotene were found to be associated with decreased risk of noninsu lin dependent diabetes mellitus, but the association disappeared after adjustment for cardiovascular risk factors.