Abstract

Background A low glycemic index (GI) diet is effective as treatment for people with diabetes and has been shown to improve pregnancy outcomes when used from the first trimester. A low GI diet is commonly advised as treatment for women with gestational diabetes mellitus (GDM). However the efficacy and pregnancy outcomes of this advice have not been systematically examined.

Objective To determine if prescribing a low glycemic index (GI) diet for women diagnosed with GDM could reduce the number of women requiring insulin without compromise of pregnancy outcomes.

Design All women with GDM seen over a 12-month period were considered for inclusion in the study. Women (n = 63) were randomised to receive either a low GI diet or a conventional high fiber (and higher GI) diet

Results Of the 31 women randomised to a low GI diet, 9 (29%) required insulin. Of the women randomised to a higher GI diet, a significantly higher proportion, 19/32 (59%), met the criteria to commence on insulin (p = 0.023). However 9 of these 19 women were able to avoid insulin use by changing to a low GI diet. Key obstetric and fetal outcomes were not significantly different.

Conclusions Using a low GI diet for women diagnosed with GDM effectively halved the number needing to use insulin with no compromise of obstetric or fetal outcomes.