Maternal metabolic response to dietary treatment for impaired glucose tolerance and gestational diabetes mellitus.

BACKGROUND: Dietary advice is a standard component of treatment for pregnant women with impaired glucose tolerance (IGT) and gestational diabetes (GDM), yet few studies report glycemic profiles in response to dietary therapies and the optimal dietary approach remains uncertain.

AIM: To assess changes in maternal glycemic profile and pregnancy outcomes among women with diet-controlled IGT and GDM.

METHODS: Pregnant women who had one or more elevated values on a 3-h oral glucose tolerance test were enrolled. All participants received dietary advice and glucose monitoring as part of routine clinical care. Fasting and 1-h post-prandial blood samples, collected prior to initiation of clinical treatment and repeated 4-6 weeks later, were analyzed for glucose, insulin, and C-peptide. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Women who required pharmacological therapy for glucose control were excluded from analyses.

RESULTS: Participants (N = 93) were of moderately older age (mean 33 years), with a high rate of overweight/obesity (mean body mass index (BMI) = 28.65 kg/m2 ), and were diagnosed late in gestation (mean 29 weeks). Fasting (mean ± SD 4.82 ± 0.53 to 4.60 ± 0.42 mmol/l; p < 0.001) and post-prandial glucose (7.01 ± 1.19 to 6.47 ± 1.10; p = 0.004) decreased significantly following the intervention. Baseline HOMA-IR was elevated (3.12 ± 1.03) but did not significantly decrease (2.78 ± 1.52; p = 0.066). There were high rates of macrosomia (24.7%) and cesarean delivery (32.3%).

CONCLUSIONS: Although improvements in blood glucose levels were observed among women with diet-controlled IGT and GDM, this was insufficient to significantly affect insulin resistance or perinatal outcome. Late diagnosis and treatment of IGT/GDM may have contributed to such outcomes.