medwireNews: A systematic review and meta-analysis highlights a potential increase in the likelihood of achieving type 2 diabetes remission on a low- or very-low-carbohydrate diet, but based on evidence of moderate or low quality.
The size of the effect was dependent of the definition of remission, however. For the definition of achieving glycated hemoglobin (HbA1c) levels below 6.5% (48 mmol/mol) with or without medications, Bradley Johnston (Texas A&M University, College Station, USA) and co-researchers found a significant 1.87-fold increased likelihood, with moderate certainty.
Specifically, the remission rate was 59 per 100 participants for 6 months of a low-carbohydrate diet, compared with 31 per 100 for a control diet, which was a low-fat diet in 78% of the 23 trials analyzed.
But for the stricter definition of HbA1c below 6.5% in the absence of glucose-lowering medications, the relative increase with low-carbohydrate versus control diets was a nonsignificant 1.24-fold with low certainty. In this case, remission rates were 16 versus 13 per 100 participants following a low-carbohydrate versus a control diet, respectively.
The analysis included a total of 1357 participants, and the number per trial ranged from 12 to 144. All trials involved a diet that provided less than 26% of calories from carbohydrates, or less than 130 g/day, and 52% met the researchers’ criteria for a very-low-carbohydrate diet, which was less than 10% of calories from carbohydrates, or less than 50 g/day.
Participants on the low-carbohydrate diets were significantly more likely to reduce their diabetes medications than those on control diets. They also lost more weight, by an average of 7.41 kg in trials with a low risk of bias.
However, the remission, medication, and weight loss benefits seen at 6 months had disappeared by 12 months, with no significant differences remaining between the low-carbohydrate and control diets, the team reports in The BMJ.
Low-carbohydrate diets were associated with significant and clinically important improvements in triglyceride levels at both 6 and 12 months.
“However, we observed a trend for clinically important increases in low density lipoprotein cholesterol at 12 months,” say the researchers.
Although the increase was nonsignificant, it exceeded the team’s predefined threshold for a minimal clinically important difference.
“Considering this and a recent systematic review of cohort studies suggesting that long term [low-carbohydrate diets] are associated with increased mortality, clinicians might consider short term [low-carbohydrate diets] for management of type 2 diabetes, while actively monitoring and adjusting diabetes medication as needed,” Johnston and team conclude.
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