Low-carb diet leads to diabetes remission at 6 months

Adherence to a low carbohydrate diet (LCD) for 6 months may result in diabetes remission without adverse consequences compared with other diets recommended for the management of type 2 diabetes (T2D), suggests a study.

“These benefits diminished at 12 months, and although LCDs seem to improve triglycerides in a clinically meaningful way, some evidence show clinical worsening of quality of life (QoL) and low-density lipoprotein cholesterol (LDL-C),” the researchers said.

The databases of CENTRAL, Medline, Embase, Cinahl, CAB, and grey literature sources were searched from inception to 25 August 2020 for randomized controlled trials evaluating LCDs (<130 g/day or <26 percent of a 2,000 kcal/day diet) and very low carbohydrate diets (VLCD; <10 percent calories from carbohydrates) for at least 12 weeks in adults with T2D.

Random effects meta-analysis was performed to calculate risk estimates and 95 percent confidence intervals (CIs). Then, the researchers assessed outcomes according to a priori determined minimal important differences to determine clinical importance, and examined heterogeneity based on risk of bias and seven a priori subgroups.

A total of 14,759 citations yielding 23 trials (n=1,357 participants) were identified, with 40.6 percent of outcomes deemed at low risk of bias. LCDs achieved higher rates of diabetes remission, defined as HbA1c <6.5 percent) than control diets (57 percent vs 31 percent; risk difference, 0.32, 95 percent CI, 0.17–0.47; eight studies; n=264; I², 58 percent) at 6 months. [BMJ 2021;372:m4743]

When a remission definition of HbA1c <6.5 percent without medication was used, smaller, nonsignificant effect sizes occurred. Remission with LCDs significantly decreased in studies that included patients on insulin, as indicated by subgroup assessments determined as meeting credibility criteria. [Adv Nutr 2016;7:994-1004; www.crd.york.ac.uk/prospero/display_record.php?RecordID=161795]

Data on remission were sparse at 12 months, ranging from a small effect to a nonsignificant increased diabetes risk. In addition, there were large clinically important improvements seen in weight loss, triglycerides, and insulin sensitivity at 6 months, which diminished at 12 months. This finding was consistent with previous studies. [Diabetes Res Clin Pract 2018;139:239-252; Diabetes Obes Metab 2019;21:15-27]

Subgroup assessments deemed credible also indicated that VLCDs were less effective than LCDs for weight loss at 6 months, but this effect was driven by diet adherence. Specifically, a clinically significant reduction in weight gain occurred among highly adherent patients on VLCDs than those who were less adherent to this diet.

At 6 months, no significant difference was observed in QoL, but participants experienced clinically important, albeit statistically nonsignificant, worsening of QoL and LDL-C at 12 months. No significant between-group differences were seen in adverse events or blood lipids at 6 and 12 months.

“We did sensitivity analyses based on risk of bias for all outcomes, but only one outcome, weight loss, showed a credible subgroup effect between studies with higher and lower risk of bias,” the researchers said. “Studies with lower risk of bias showed more dramatic increases in weight loss, findings that were both statistically and clinically significant, supporting our overall findings.”

The current study was limited by continued debate around what constitutes diabetes remission, as well as the efficacy, safety, and dietary satisfaction of longer-term LCDs.