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Low-Glycemic Index Diet Doesn’t Change Outcomes with Gestational Diabetes

Sep 30, 2011

Pregnancy outcomes with gestational diabetes are similar whether women follow a low-glycemic index (LGI) diet or a conventional high-fiber diet, according to a study….

The authors conclude, “An LGI diet appears to be a safe alternative to the traditional pregnancy diet for women with GDM (gestational diabetes mellitus) and expands the range of dietary strategies that can be offered.”

Dr. Jennie Brand-Miller, at the University of Sydney, and colleagues had hoped that a low-glycemic index diet would represent a way to reduce postprandial glucose in gestational diabetes without restricting carbohydrates — and that such an effect might help avoid excessive birth weight.

Their randomized controlled trial included 99 women diagnosed with gestational diabetes at 20-32 weeks’ gestation. They assigned the women to one of two healthy diets containing similar proportions of protein, fat and carbohydrate — but one with a low glycemic index (target GI <50) and the other with a high-fiber (HF) content and moderate GI (target GI ~60).

Fewer women gained excessive weight on the LGI diet (25%) than the HF diet (42%), and fewer needed insulin treatment (53% vs. 61%), the team found.

However, neonatal outcomes were virtually the same in both groups. Mean birth weight in both arms was 3.3 kg (p=0.619), the rate of macrosomia was 2.1% with the LGI diet compared to 6.7% on the HF diet (p=0.286), and the ponderal index was 27.2 versus 27.0 kg/m3 (p=0.614) in the two groups, respectively, Dr. Brand-Miller and colleagues report.

“Contrary to our hypothesis,” they conclude, “this randomized controlled trial of an LGI diet versus a conventional high-fiber diet found no differences in key pregnancy outcomes in GDM.”

Diabetes Care 2011, online September 6, 2011