Background: Globally, type 2 diabetes mellitus (T2DM) is one of the most common diseases, and the incidence is gradually increasing. Diet management could improve the elevated HbA1c levels. Aim: This review aims to examine the effects of different types of diets on glycemic control in patients with T2DM. Methods: PubMed and Google scholar databases were searched. Reports published from the years 1991 to 2021 that focused on the effect of different diets on diabetes control were selected. Results: All the studies reported that the type of diet can affect insulin secretion and glycemic control in patients with diabetes. The recommended macronutrient distribution for patients with diabetes is 30% of fat, 45–60% of carbohydrates, and 15–35% of protein. Consuming more or less of these macronutrients may lead to changes in glucose metabolism and may affect insulin secretion. In fact, following alow-fat diet improves glycemic control and decreases HbA1c levels. Studies reported that a low-carbohydrate diet had the greatest effect on improving glycemic control and insulin parameters. A low-calorie diet reduced fasting plasma glucose, while a very low-calorie diet resulted in a long-term decrease in HbA1c level. A healthy diet free of processed foods and sugar, and rich in nutrients such as fiber, vitamins, and minerals contributed to maintaining controlled blood sugar and lipid plasma levels. Although studies show a low-salt diet improves blood pressure, which is common inT2DM, other findings show that restricting salt intake is associated with increased sugar consumption. Conclusion: Healthy diet with adequate intake of energy and low-fat and low-sugar foods can enhance the glycemic control and reduce T2DM complications.

BackgroundDiabetes mellitus type 2 (T2DM) is one of the most common diseases worldwide. Unhealthy dietary habits may lead to T2DM, which is also influenced by the extent of education and knowledge of appropriate diets for this disease.AimThis study aims to highlight the possible association between following different types of diet (low-fat diet, low-calorie diet, low-salt diet, and more than one diet) and glycemic control among Qatari and long-term resident patients with T2DM.MethodsThis study is secondary data analysis. Qatar Biobank (QBB) data on 2448 T2DM patients aged 18–60 years were obtained. The first group included participants with HbA1C <7%, while the second included those with HbA1c ≥ 7%.ResultsThe results of the association of glycemic control with different diets followed by patients with type 2 diabetes were adjusted in four models. In the 4th model (adjusted for gender, age, sociodemographic, anthropometric, dietary habits, comorbidities, and medications), results showed that poor patients with poor glycemic control have higher odds [OR 1.90; CI (1–3.63)] of following a low-salt diet. The same observation was found in the low-fat diet [OR 1.73; CI (1.06-3.07)]. However, patients following more than one diet showed lower odds of having poor glycemic control for about 32% [OR.69; CI (0.48–0.98)].ConclusionDiet and lifestyle are vital factors that can affect HbA1C levels. The findings of this secondary analysis showed that better glycemic control of the patients was observed in patients following more than diet from the studied diets.