Following a low glycaemic diet confers small but important benefits in blood glucose levels, cholesterol, weight and other risk factors, according to a study published by The BMJ.
The improvements were over and above existing drug and insulin therapy, suggesting this diet may help complement treatment, said the researchers.
Research has shown that foods with a low glycaemic index (GI), which is a measure of how quickly a food affects blood glucose levels relative to white bread, can help keep blood sugar levels steady and reduce the risk of heart disease in people with diabetes. These include foods such as vegetables, most fruits, pulses and wholegrains.
Due to this, clinical guidelines across the world recommend a low GI or GL (glycaemic load) diet for people with diabetes. However, the last European Association for the Study of Diabetes (EASD) guidelines were released over 15 years ago and since that time a number of trials have been published.
So researchers set out to summarise the effect of low GI/GL dietary patterns on blood sugar control and other known risk factors in diabetes to help inform the update of the EASD guidelines for nutrition treatment.
Their results are based on 27 randomised controlled trials published up to May 2021 investigating the effect of diets with low GI/GL in diabetes for three or more weeks.
The trial recruited a total of 1617 participants with type 1 or 2 diabetes, who were predominantly middle aged, overweight or obese with moderately controlled type 2 diabetes treated with drugs or insulin.
Though the trials varied quality, the researchers could assess the certainty of evidence using the recognised GRADE system.
The results show that low-GI/GL dietary patterns were linked to small but clinically meaningful reductions in blood sugar levels (HbA1c) compared with higher-GI/GL control diets.
Some other risk factors saw changes, such as fasting glucose (blood sugar levels after a period of fasting), LDL cholesterol, body weight, and C-reactive protein (a chemical associated with inflammation), but not blood insulin levels, HDL cholesterol, waist circumference, or blood pressure. The certainty of evidence was high for reduction in blood sugar levels and moderate for most other outcomes.
Limitations that included imprecision in the evidence for the effect of low GI/GL dietary patterns on LDL cholesterol and waist circumference, and the small number of available trial comparisons for blood pressure and inflammatory markers.
However, they say their findings show that low GI/GL dietary patterns “are considered an acceptable and safe dietary strategy that can produce small meaningful reductions in the primary target for glycaemic control in diabetes, HbA1c, fasting glucose, and other established cardiometabolic risk factors.”
“Our synthesis supports existing recommendations for the use of low GI/GL dietary patterns in the management of diabetes,” they concluded.