Carbohydrate quantity in the dietary management of type 2 diabetes: A systematic review and meta-analysis

This systematic review and meta-analysis (registration number: CRD42013005825) compares the effects of low carbohydrate diets (LCDs) on body weight, glycaemic control, lipid profile and blood pressure with the effects of higher carbohydrate diets (HCDs) in adults with type 2 diabetes.

MEDLINE, EMBASE, CENTRAL, CINAHL, Food Science Source and SweMed+ databases were systematically searched to identify randomized controlled trials (duration ≥3 months) investigating the effects of an LCD compared to an HCD in the management of type 2 diabetes. Data were extracted and pooled using a random effects model and were expressed as mean differences and risk ratio. Subgroup analyses were undertaken to examine the effects of duration of intervention, extent of carbohydrate restriction and risk of bias. The certainty of evidence was assessed using GRADE.

Of the 1589 studies identified, 23, including 2178 participants, met inclusion criteria. Reductions were slightly greater with LCDs than with HCDs for HbA1c (-1.0 mmol/mol; CI, -1.9, -0.1 [-0.09%; CI, -0.17, -0.01]) and for triglycerides (-0.13 mmol/L; CI, -0.24, -0.02). Changes in weight, HDL- and LDL-cholesterol, total cholesterol and blood pressure did not differ significantly between groups. Subgroup analyses suggested that the difference in HbA1c was evident only in studies with a duration of ≤6 months and with a high risk of bias.

The proportion of daily energy provided by carbohydrate intake is not an important determinant of response to dietary management, especially when considering longer term trials. A range of dietary patterns, including those traditional in Mediterranean countries, seems suitable for translating nutritional recommendations for individuals with diabetes into practical advice.