The effect of a low-carbohydrate high-fat diet and ethnicity on daily glucose profile in type 2 diabetes determined by continuous glucose monitoring

Background and aims: Nutrition is an integral part of type 2 diabetes (T2DM) treatment, but the optimal macronutrient composition is still debated and previous studies have not addressed the role of ethnicity in dietary response. The current study aims were to compare the effect of short-term glycemic response to low-carbohydrate high-fat (LC-HF) diet vs. high-carbohydrate low-fat (HC-LF) diet using continuous glucose monitoring (CGM) and to evaluate the response of individuals with T2DM of Yemenite (Y-DM) and non-Yemenite origin (NY-DM). Methods: Twenty T2DM males, ten Y-DM and ten NY-DM underwent meal tolerance test and indexes of insulin resistance and secretion were calculated. Subsequently, patients were connected to CGM to assess daily glycemic control and glucose variability in response to isocaloric HC-LF or LC-HF diet, receiving each diet for 2 days by providing prepared meals. Daily glucose levels, area under the glucose curve (G-AUC) and parameters of glucose variability [standard deviation (SD), mean amplitude of glycemic excursions (MAGE) and mean absolute glucose (MAG)] were evaluated. Results: The LC-HF resulted in a significantly lower G-AUC (p < 0.001) and in lower variability parameters (p < 0.001) vs. the HC-LF diet. However, Y-DM showed less reduction in glucose variability indices upon diet-switching vs. NY-DM; MAGE decreased, respectively, by 69% vs. 89%, p = 0.043 and MAG by 34% vs. 45%, p = 0.007 in Y-DM compared to NY-DM. Conclusions: These results suggest that LC-HF diet is effective in reducing glycemic fluctuation in T2DM and that ethnicity may have a role in the response to dietary regime.