medwireNews: Randomized trial findings show reduced glycated hemoglobin (HbA1c) and bodyweight in people with type 2 diabetes following a calorie-unrestricted low-carbohydrate, high-fat (LCHF) diet versus a high-carbohydrate, low-fat (HCLF) approach.
“The 9.5 mmol/mol (0.88%) reduction in HbA1c in participants on the LCHF diet is similar to many antidiabetic medications, such as dipeptidyl peptidase-4 antagonists, sodium–glucose cotransporter-2 antagonists, and sulfonylureas,” write the researchers in the Annals of Internal Medicine.
The average baseline HbA1c was 54.5 mmol/mol (7.14%) in the 110 people assigned to the LCHF group and 57.9 mmol/mol (7.45%) in the 55 assigned to the HCLF diet. During 6 months of following the respective diets, these values fell by 9.52 mmol/mol (0.88%) and 3.47 mmol/mol (0.29%), giving a significant between-group difference of 6.05 mmol/mol (0.59%).
But 3 months after stopping the diets, these reductions were smaller and the between-group difference had lost statistical significance, highlighting the need for long-term dietary change to maintain the benefits.
“Because this diet was calorie-unrestricted, long-term adherence may be more likely, but this warrants future study,” say Aleksander Krag (Odense University Hospital, Denmark) and co-investigators.
Bodyweight fell by an average of 5.5 kg in the LCHF group and 1.7 kg in the HCLF group, with the 3.8 kg difference between the groups being statistically significant. Again, these benefits were mostly lost 3 months after reverting to usual eating patterns.
Given the weight loss, the researchers say that “it is unclear if changes in macronutrient composition or the weight loss itself is the main driver of the HbA1c improvement.”
However, they note that the “LCHF group lost more weight than the HCLF group despite a higher reported calorie intake.”
Levels of low-density lipoprotein (LDL) cholesterol increased significantly more in the LCHF than HCLF group, by an average of 0.37 mmol/L (14.29 mg/dL).
But Krag and team note that the absolute increase in the LCHF group was “a mere 0.23 mmol/L (8.8 mg/dL)” and that there were small improvements in levels of high-density lipoprotein cholesterol and triglycerides and a significant improvement in insulin resistance versus the HCLF group.
“In sum, we consider the beneficial effects of the LCHF diet to outweigh the minor increase in LDL cholesterol induced by the diet,” they write.
The researchers had also intended to examine the effects of the diets on nonalcoholic fatty liver disease (NAFLD). However, both groups had improvements in the NAFLD Activity Score (NAS), with no significant difference between them, and the baseline median score of NAS of 3 points “also made it difficult to show a 2 or more points improvement” as intended.
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Ann Intern Med 2022; doi:10.7326/M22-1787