Sex Differences in the Association Between Serum Ferritin and Fasting Glucose in Type 2 Diabetes Among South Asian Surinamese, African Surinamese, and Ethnic Dutch :The population-based SUNSET study

Louise H. Dekker, MSC, Mary Nicolaou, PHD, Daphne L. van der A, PHD, Wim B. Busschers, MSC, Lizzy M. Brewster, PHD, Marieke B. Snijder, PHD, Karien Stronks, PHD and Irene G.M. van Valkengoed, PHD

Published online before print November 19, 2012, doi: 10.2337/dc12-1243

Diabetes Care November 19, 2012

Abstract
OBJECTIVE Moderately elevated iron stores below the levels commonly associated with hemochromatosis have been implicated in the etiology of diabetes. Studies suggest that iron status (measured by serum ferritin) differs significantly according to sex, but inconsistent findings have been reported. Our aim is to test the association between serum ferritin and the prevalence of type 2 diabetes and fasting glucose concentrations in a population-based, multiethnic, cross-sectional study including men and women of African Surinamese, South Asian Surinamese, and ethnic Dutch origin.

RESEARCH DESIGN AND METHODS We analyzed data on 508 ethnic Dutch, 597 African Surinamese, and 339 South Asian Surinamese aged 35–60 years. Type 2 diabetes was defined as a fasting plasma glucose level ≥7.0 mmol/L or a self-reported diagnosis.

RESULTS Serum ferritin was positively associated with type 2 diabetes and fasting glucose, but differences in the associations according to sex were observed. Serum ferritin concentration was positively associated with type 2 diabetes among women in all ethnic groups (odds ratio [OR] ethnic Dutch: 1.07 [95% CI 1.01–1.13]; OR South Asian Surinamese: 1.05 [1.00–1.10]; OR African Surinamese: 1.05 [1.01–1.10]), but not among men. Serum ferritin was also more strongly associated with fasting glucose in women than in men. Moreover, the magnitude of sex differences in the association between serum ferritin and fasting glucose, but not type 2 diabetes, was more pronounced in the African Surinamese group than in the other ethnic groups (P for interaction ≤0.0001).

CONCLUSIONS We found a positive association between serum ferritin and type 2 diabetes and fasting glucose in our multiethnic population, which appeared stronger among women than men. Further evaluation of the variation in sex differences between ethnic groups is warranted, particularly among the African Surinamese, to understand the mechanisms behind these sex differences.