Low Carbohydrate-Diet Scores and Long-term Risk of Type 2 Diabetes AmongWomen with a History of Gestational Diabetes Mellitus: A Prospective Cohort Study

OBJECTIVE Low-carbohydrate diets (LCDs) may improve short-term glycemic control in patients with gestational diabetes mellitus (GDM), but the long-term effect on progression from GDM to type 2 diabetes mellitus (T2DM) is unknown. We aimed to examine the long-term risk of T2DM in association with a low-carbohydrate dietary pattern among women with a history of GDM. RESEARCH DESIGN AND METHODS Overall, 4,502 women with a history of GDM from the Nurse's Health Study II (NHSII) cohort, as part of the Diabetes & Women's Health (DWH) study, were followed up from 1991 to 2011. Overall, animal, or vegetable LCD scores, which represent adherence to different low-carbohydrate dietary patterns, were calculated using diet intake information assessed every 4 years since 1991 by validated food-frequency questionnaires. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CIs. RESULTS We documented 722 incident cases of T2DM during 68,897 person-years of observation. The multivariable-adjusted HRs (95% CIs) of T2DM, comparing the highest with lowest quintiles, were 1.36 (1.04-1.78) for overall LCD score (P = 0.003 for trend), 1.40 (1.06-1.84) for animal LCD score (P = 0.004 for trend), and 1.19 (0.91- 1.55) for vegetable LCD score (P = 0.50 for trend). CONCLUSIONS Among women with a history of GDM, a low-carbohydrate dietary pattern, particularly with high protein and fat intake mainly from animal-source foods, is associated with higher T2DM risk, whereas a low-carbohydrate dietary pattern with high protein and fat intake from plant-source foods is not significantly associated with risk of T2DM.