OBJECTIVE: To systematically review and critically appraise medical nutrition therapy guidelines for treating patients with gestational diabetes mellitus.
DESIGN: We searched Medline, the Cochrane Library, Guidelines International Network, and Google Scholar to retrieve clinical practice guidelines (CPGs) for medical nutrition therapy in gestational diabetes mellitus from professional or governmental organizations, published in English, between January 1, 2007, and November 24, 2018. CPGs were reviewed and appraised using the Appraisal of Guidelines, Research, and Evaluation II instrument.
RESULTS: Of 1,286 retrieved articles, 21 CPGs fulfilled the inclusion criteria. CPGs of the Academy of Nutrition and Dietetics, Diabetes Canada, and Malaysia Health Technology Assessment Section received the greatest overall scores and the highest scores concerning rigor of recommendations development. Many CPGs failed to involve multidisciplinary teams in their development, including patients, and often, dietitians. Applicability of the recommendations was low, lacking facilitators and tools to enhance implementation. Many CPGs demonstrated low editorial independence by failing to disclose funding and competing interests. More medical nutrition therapy recommendations were incorporated in the Academy of Nutrition and Dietetics and Malaysia Health Technology Assessment Section CPGs. The Malaysia Health Technology Assessment Section, Diabetes Canada, Academy of Nutrition and Dietetics, and Endocrine Society guidelines were recommended by the review panel herein without modifications. Overall, the CPGs suggested the consumption of adequate protein and the selection of foods with low glycemic index, divided into three main meals and two to four snacks. Weight gain recommendations were mostly based on the Institute of Medicine body mass index thresholds.
CONCLUSIONS: With few exceptions, the main developmental limitations of the appraised CPGs involved low rigor of recommendations development, lack of multidisciplinary stakeholder involvement, low applicability, and inadequate editorial independence. This indicates a need for developing more clear, unbiased, practical, and evidence-based CPGs.
METHODS: A double blind randomized trial. 103 women scheduled to receive two doses of 12-mg intramuscular dexamethasone 12-hour apart were separately randomized to take prophylactic metformin or placebo after stratification according to their gestational diabetes (GDM) status. First oral dose of allocated study drug was taken at enrolment and continued 500 mg twice daily for 72 hours if not delivered. Six-point blood sugar profiles were obtained each day (pre- and two-hour post breakfast, lunch and dinner) for up to three consecutive days. A hyperglycemic episode is defined as capillary glucose fasting/pre-meal ≥ 5.3 mmol/L or two-hour post prandial/meal ≥ 6.7 mmol/L. Primary outcome was hyperglycemic episodes on Day-1 (first six blood sugar profile points) following antenatal corticosteroids.
RESULTS: Number of hyperglycemic episodes on the first day were not significantly different (mean ± standard deviation) 3.9 ± 1.4 (metformin) vs. 4.1 ± 1.6 (placebo) p = 0.64. Hyperglycemic episodes markedly reduced on second day in both arms to 0.9 ± 1.0 (metformin) vs. 1.2 ± 1.0 (placebo) p = 0.15 and further reduced to 0.6 ± 1.0 (metformin) vs. 0.7 ± 1.0 (placebo) p = 0.67 on third day. Hypoglycemic episodes during the 3-day study period were few and all other secondary outcomes were not significantly different.
CONCLUSIONS: In euglycemic and diet controllable gestational diabetes mellitus women, antenatal corticosteroids cause sustained maternal hyperglycemia only on Day-1. The magnitude of Day-1 hyperglycemia is generally low. Prophylactic metformin does not reduce antenatal corticosteroids' hyperglycemic effect.
TRIAL REGISTRATION: The trial is registered in the ISRCTN registry on May 4 2017 with trial identifier https://doi.org/10.1186/ISRCTN10156101 .