Low-Carb Diet May Reduce HbA1c More Than Low-Fat Diet in T2D
Low-carbohydrate diets were associated with greater decreases in fasting glucose concentrations than low-fat diets.
Carbohydrate restriction demonstrates slightly improved metabolic control compared with dietary fat restriction in individuals with type 2 diabetes (T2D), according to a systematic review published in The American Journal of Clinical Nutrition.
Researchers relied on randomized control trials and controlled clinical trials that compared 2 diets, specifically low carbohydrate intake (≤40% of energy) and low fat intake (≤30%) in adults with T2D. When looking at past trial bias, researchers applied the Cochrane Collaborations domain-based assessment tool to gauge the accuracy of evidence and reliability of outcomes. In total, 36 studies met the researcher's criteria and were included.
The change from baseline in glycated hemoglobin (HbA1c) in participants on a low-carbohydrate diet was greater in the short term than in those on a low-fat diet (mean difference: –1.38%; 95% CI: –2.64% to –0.11%). This difference was too low to be statistically significant and diminished over time, disappearing by 2 years after baseline. Fasting plasma glucose was also decreased to a greater extent among patients on a low-carbohydrate diet.
Researchers concluded that a low-carbohydrate diet in the short term (1 year) may reduce HbA1c better than a low-fat diet. “This analysis,” according to researchers, “does not support the long-held preference for low-fat diets as the default dietary intervention for T2D. Instead, the results suggest that, if it fits the patients' preferences, restriction of carbohydrates may be slightly better.”
This study was funded by the Dutch Diabetes Foundation and an unrestricted grant from Sanof.
van Zuuren EJ, Fedorowicz Z, Kuijpers T, Pijl H. Effects of low-carbohydrate- compared with low-fat-diet interventions on metabolic control in people with type 2 diabetes: a systematic review including GRADE assessments [published online July 11, 2018]. Am J Clin Nutr. doi: 10.1093/ajcn/nqy096