Objective To systematically evaluate relevant guidelines on calories and 3 nutrients allocations during pregnancy in patients with gestational diabetes mellitus,and to compare the similarities and differences in recommendations between these guidelines.Methods Domestic and foreign guideline networks,websites of specialist associations related to diabetes,obstetrics and gynecology,as well as databases,were systematically searched from January 2010 to June 2022.There were 2 appraisers who used the Appraisal of Guidelines for Research &Evaluation Ⅱ to evaluate the quality of guidelines and then used the content analysis method to synthesize the recommendations of each guideline and compare similarities and differences.Results This study included 18 guidelines with fair overall quality(10 with grade A,2 with grade B and 6 with grade C).The guidelines provided recommendations in 5 aspects of meal allocation,calories,carbohydrates,proteins,and fats,totaling 57 recommendations.While the recommendations for meal allocation were consistent across guidelines,there were significant differences in the recommendations for calories and the 3 major nutrients.Conclusion The recommendations regarding the distribution of calories and the 3 major nutrients mostly rely on expert consensuses,with low-quality evidence but mostly strong recommendations.These guidelines exhibit significant variations from one to another.Consequently,future studies with higher quality on the distribution of calories and 3 nutrients should be conducted,and high-quality evidence-based nutrition guidelines for gestational diabetes should be developed in China.