Systematic Review of Nutritional Guidelines for the Management of Gestational Diabetes Mellitus: A Global Comparison.

Gestational diabetes mellitus (GDM) affects 7-9% of pregnancies worldwide and is associated with adverse maternal and neonatal outcomes. Nutritional therapy is a key component of GDM management. However, inconsistencies exist across international and national guidelines regarding macronutrient distribution, glycemic targets, and micronutrient supplementation. This systematic review aims to compare updated nutritional recommendations for GDM across major health organizations and identify areas of consensus, divergence, and evidence gaps. This systematic review was conducted following PRISMA guidelines and registered in PROSPERO (CRD420251026194). A comprehensive literature search was performed in PubMed, Scopus, and Google Scholar (concluding March 2025), along with manual searches of official websites of professional health organizations (e.g., ADA, WHO, NICE, IDF). Guidelines published within the last 10 years (or the most relevant national guideline if slightly older), available in English or with access to translation, and including explicit nutritional recommendations for GDM were included. Data were extracted on macronutrient composition, glycemic targets, and micronutrient supplementation, with evaluation of the supporting evidence and regional context, incorporating findings from recent key guideline updates. In total, 12 guidelines met the inclusion criteria. While all guidelines emphasized carbohydrate moderation and adequate fiber intake, significant discrepancies were found in carbohydrate quality recommendations (e.g., low-glycemic index focus vs. total carbohydrate restriction), postprandial glucose targets (e.g., 1-h vs. 2-h measurements and varying thresholds like <120 vs. <140 mg/dL), and the use of non-routine micronutrients such as chromium, selenium, and omega-3 fatty acids (generally lacking endorsement). Recent updates from key bodies like ADA, Diabetes Canada, and KDA largely maintain these core stances but show increasing emphasis on dietary patterns and acknowledgement of CGM technology, without resolving key discrepancies. Cultural adaptability and behavioral counselling strategies were minimally addressed across most guidelines. Despite general agreement on the principal recommendations of nutritional management in GDM, substantial variation persists in specific recommendations, even considering recent updates. Consistent, evidence-based, and culturally adaptable guidelines incorporating implementation strategies are needed to optimize care and reduce disparities in GDM management across regions.