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. 2011 Jul;34(7):1557-63.
doi: 10.2337/dc11-0134.

A prospective study of prepregnancy dietary iron intake and risk for gestational diabetes mellitus

Katherine Bowers  1 , Edwina Yeung, Michelle A Williams, Lu Qi, Deirdre K Tobias, Frank B Hu, Cuilin Zhang
Affiliations

A prospective study of prepregnancy dietary iron intake and risk for gestational diabetes mellitus

Katherine Bowers et al. Diabetes Care. 2011 Jul.

Abstract

Objective: It is important to identify modifiable factors that may lower gestational diabetes mellitus (GDM) risk. Dietary iron is of particular interest given that iron is a strong prooxidant, and high body iron levels can damage pancreatic β-cell function and impair glucose metabolism. The current study is to determine if prepregnancy dietary and supplemental iron intakes are associated with the risk of GDM.

Research design and methods: A prospective study was conducted among 13,475 women who reported a singleton pregnancy between 1991 and 2001 in the Nurses' Health Study II. A total of 867 incident GDM cases were reported. Pooled logistic regression was used to estimate the relative risk (RR) of GDM by quintiles of iron intake controlling for dietary and nondietary risk factors.

Results: Dietary heme iron intake was positively and significantly associated with GDM risk. After adjusting for age, BMI, and other risk factors, RRs (95% CIs) across increasing quintiles of heme iron were 1.0 (reference), 1.11 (0.87-1.43), 1.31 (1.03-1.68), 1.51 (1.17-1.93), and 1.58 (1.21-2.08), respectively (P for linear trend 0.0001). The multivariate adjusted RR for GDM associated with every 0.5-mg per day of increase in intake was 1.22 (1.10-1.36). No significant associations were observed between total dietary, nonheme, or supplemental iron intake and GDM risk.

Conclusions: These findings suggest that higher prepregnancy intake of dietary heme iron is associated with an increased GDM risk.

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Figures

Figure 1
Figure 1
Smoothed histogram and spline plot displaying the RRs of GDM according to dietary heme iron intake (mg/day, continuous). RRs adjusted for age, parity, BMI, physical activity, glycemic load, polyunsaturated fat intake, cereal fiber, smoking, alcohol, total calories, and family history of diabetes. The solid lines represent point estimates; the dashed lines illustrate 95% CIs.
Figure 2
Figure 2
RRs of GDM in association with prepregnancy dietary heme iron intake stratified by smoking status. RRs are adjusted for age, parity, BMI, physical activity, glycemic load, polyunsaturated fat intake, cereal fiber, alcohol, total calories, and family history of diabetes. Smokers are represented by diamonds, and nonsmokers are represented by squares. (A high-quality color representation of this figure is available in the online issue.)
See this image and copyright information in PMC

Comment in

  • Iron and diabetes revisited.
    Shah SV, Fonseca VA. Shah SV, et al. Diabetes Care. 2011 Jul;34(7):1676-7. doi: 10.2337/dc11-0700. Diabetes Care. 2011. PMID: 21709301 Free PMC article. No abstract available.

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