Post-gestational diabetes mellitus (GDM) women are recommended weight loss to manage increased cardio-metabolic risks. We investigated the effects of lowering diet glycaemic index (GI) on fasting blood glucose (FBG), serum lipids, body weight and composition of post-GDM women with varying fasting insulin levels (INS). Seventy-seven Asian, non-diabetic women with previous GDM (aged 20-40 years, mean BMI: 26.4+/-4.6 kg m(-2)) were recruited. At baseline, 20 subjects with INS <2 muIU ml(-1) and 18 with INS >/=2 muIU ml(-1) received conventional dietary recommendations (CHDR) only. CHDR emphasised energy and fat intake restriction and encouraged increase in dietary fibre intakes. Twenty-four subjects with INS <2 muIU ml(-1) and 15 with INS ≥2 muIU ml(-1), in addition to CHDR, received low-GI education (LGI). Changes in FBG, serum lipids, body weight and body composition were evaluated. Subjects with INS <2 muIU ml(-1) had similar outcomes with both diets. After 1 year, subjects with INS ≥2 muIU ml(-1) who received LGI education had reductions in FBG and triglycerides. Subjects who received CHDR observed increase in both FBG and triglycerides (P<0.05). Among all subjects, diet GI was lower and dietary fibre intakes were higher in LGI compared with CHDR subjects (all P<0.05). Thus, in Asian post-GDM women with normal/higher INS, adding low-GI education to CHDR improved management of FBG and triglycerides.