Low-carb diet lowers glucose in absence of medication

A low-carbohydrate dietary intervention helps with glucose control in individuals with elevated HbA1c but not taking glucose-lowering medications, as shown in a study.

Researchers conducted a 6-month randomized clinical trial examining the effect of a behavioural intervention promoting a low-carbohydrate diet vs usual diet on 6-month changes in HbA1c among individuals aged 40–70 years with elevated untreated HbA1c (6.0–6.9 percent [42–52 mmol/mol]).

A total of 2,722 individuals were enlisted, among whom 962 underwent screening, and 150 (mean age 58.9 years, 72 percent female, 59 percent Black) were randomized to either the low-carbohydrate diet intervention (n=75) or usual diet (n=75).

Participants who underwent a low-carbohydrate diet intervention received dietary counselling. They had a target intake of <40 net grams of carbohydrates during the first 3 months and of <60 net grams for months 3 to 6.

Six-month data were available for 142 participants (95 percent). The mean HbA1c was 6.16 percent at baseline. The primary outcome of a 6-month change in HbA1c was significantly greater in the low-carbohydrate diet intervention group vs the usual diet group (net difference, –0.23 percent, 95 percent confidence interval [CI], –0.32 to –0.14; p<0.001).

The same was true for other outcomes, with the low-carbohydrate diet intervention group achieving greater improvements in fasting plasma glucose (–10.3 mg/dL, 95 percent CI, –15.6 to –4.9 mg/dL; p<0.001) and body weight (–5.9 kg, 95 percent CI, –7.4 to –4.4; p<0.001).

The study was unable to evaluate the effects of the low-carbohydrate diet intervention independently of weight loss. Nevertheless, the researchers believe that although more research is needed, the diet might be a useful dietary approach for preventing and treating type 2 diabetes if sustained.