Carbohydrate-restricted diets, in particular those that restrict carbohydrate to < 26% of total energy, produced greater reductions in HbA1c at 3 months (WMD -0.47%, 95% CI: -0.71, -0.23) and 6 months (WMD -0.36%, 95% CI: -0.62, -0.09), with no significant difference at 12 or 24 months. There was no difference between moderately restricted (26-45% of total energy) and high carbohydrate diets at any time point. Although there are issues with the quality of the evidence, this review suggests that carbohydrate-restricted diets could be offered to people living with diabetes as part of an individualised management plan.
Sainsbury (2018). "Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis." Diabetes Res Clin Pract.