Serum antioxidants and risk of non‐insulin dependent diabetes mellitus

Abstract

Objective: To examine whether serum levels of a-tocopherol, b-carotene 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. Serum 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 a-tocopherol and b-carotene levels than controls. The relative risk between the highest and lowest tertiles of serum a-tocopherol was 0.61 (95% con®dence interval (CI) 0.32±1.15), between the highest and lowest tertiles of serum b-carotene 0.45 (CI 0.22±0.92). Although the relative risk of highest compared with lowest tertile of serum a-tocopherol was not statistically signi®cant the inverse trend through the tertiles was (P`0.05). The decreasing risk of diabetes was particularly evident in the elderly, women, nonsmokers and the obese. However, adjustment for serum cholesterol, obesity, smoking and hypertension abolished the associations. The adjusted relative risks in relation to serum a-tocopherol and bcarotene (between highest and lowest tertiles) were 1.25 (CI 0.54±2.90) and 0.94 (CI 0.38±2.32), respectively. No associations were observed relating to serum retinol. Conclusions: High levels of a-tocopherol and b-carotene were found to be associated with decreased risk of noninsulin dependent diabetes mellitus, but the association disappeared after adjustment for cardiovascular risk factors.

Effect of α-tocopherol and β-carotene supplementation on the incidence of type 2 diabetes

“…These findings contradict the results of two prospective observational studies, from Finland and the USA, in which a low concentration of plasma vitamin E was associated with excess risk of type 2 diabetes [4,5]. In a Finnish prospective study, the inverse association between serum α-tocopherol and β-carotene and the incidence of diabetes disappeared after adjustment for cardiovascular risk factors [3]. The numbers of incident cases of diabetes in these three studies were small, however, ranging from 45 to 106.…”

“…Oxidative stress mediated by free radicals has been implicated in the pathogenesis of diabetes, and thus antioxidants could protect against diabetes [1]. However, only a few human studies have examined the association between antioxidant status and the risk of type 2 diabetes and the findings have been contradictory [2][3][4][5][6].…”

Intake of antioxidants and risk of type 2 diabetes in a cohort of male smokers

“…Akbaraly et al, 2008). However, in an other Finnish study there was no association between baseline serum a-tocopherol or b-carotene concentrations and risk of incident type 2 diabetes (Reunanen et al, 1998). Neither baseline serum a-tocopherol nor b-carotene concentrations were associated with decreased risk of type 2 diabetes in the ATBC Study cohort (Kataja-Tuomola et al, 2008).…”

Food consumption and the incidence of type II diabetes mellitus

“…In several epidemiological studies, intakes or serum levels of vitamin C, vitamin E, or carotenoids have been inversely associated with diabetes (Chatterjee & Banerjee, 1979;Sinclair et al, 1994;Feskens et al, 1995;Salonen et al, 1995;Abahusain et al, 1999;Ford et al, 1999;Knekt et al, 1999;Will et al, 1999;Polidori et al, 2000;Montonen et al, 2004b). However, the findings on the relation between antioxidants and glucose metabolism are not consistent (Sanchez-Lugo et al, 1997;Reunanen et al, 1998;Liu et al, 1999). Moreover, flavonoids may provide protection against chronic diseases by their free radical scavenging properties.…”