Background: To date, there is no protocol providing dietary guidelines to assist health care professionals in counseling Brazilian individuals with Diabetes Mellitus (DM) assisted in primary health care (PHC) according to the Dietary Guidelines for the Brazilian Population (DGBP). Therefore, this study aimed to develop and validate a protocol based on the DGBP for health care, non-nutritionist professionals in counseling adults with DM in PHC. Methods: We systematized the recommendations published in the DGBP, the Diabetes Brazilian Society guidelines, and the scientific literature regarding food and nutrition needs of adults with DM. The clarity and relevance were validated by an expert panel (n = 19) and the understanding and applicability were validated by PHC professionals (n = 12). The degree of agreement of the experts was assessed using a Content Validity Index (CVI). Items receiving CVI > 0.8 were considered appropriate. Results: The protocol consisted of six dietary recommendations that encouraged the daily consumption of beans, vegetables, and fruits, advised the avoidance of sugar-sweetened beverages and ultra-processed foods, stimulated eating in appropriate environments, and gave additional guidance addressed to the particularities of DM. The protocol clarity, relevance, and applicability were successfully validated. Conclusion: The protocol supports health care, non-nutritionist professionals in the guidance of dietary recommendations and promoting adequate and healthy eating habits for adults with DM in PHC.