Lower carbohydrate and higher fat intakes linked to higher HbA1c

Takeaway

• Lower carbohydrate and higher fat intakes are associated with higher glycated haemoglobin (HbA1c) and increased odds of having type 2 diabetes mellitus (T2DM).

Why this matters

• Findings do not support low carbohydrate diets for prevention of T2DM.

Study design

• This population-based cross-sectional study investigated whether carbohydrate intake and low-carbohydrate, high-fat (LCHF) dietary pattern relate to HbA1c concentration and T2DM prevalence (n=3234; diabetes diagnosis: n=104; without diagnosed diabetes: n=3130; aged ≥16 years).
• LCHF scores (0–20, a higher score indicating lower % food energy from carbohydrate, with reciprocal higher contribution from fat) and UK Dietary Reference Value (DRV) scores (0–16, based on UK dietary recommendations) were calculated.
• Funding: None disclosed.

Key results

• Mean intake energy was 48.0% for carbohydrates, and 34.9% for total fat.
• Every 5% food energy increase in carbohydrate and fat was associated with 12% lower risk of having diabetes (OR, 0.88; 95% CI, 0.78-0.99; P=.03) and 17% higher risk for diabetes (OR, 1.17; 95% CI, 1.02-1.33; P=.022), respectively.
• Each 2-point increase in LCHF score was related to 8% (OR, 1.08; 95% CI, 1.02-1.14; P=.006) higher risk for diabetes, whereas there was no evidence for an association between DRV score and diabetes.
• In those without diagnosed diabetes, every 5% energy increase in carbohydrate was associated with decrease in HbA1c percentage (−0.016%, 95% CI, −0.029 to −0.004%; P=.012), whereas every 5% energy increase in fat was associated with increased HbA1c percentage by 0.029% (95% CI, 0.015-0.043%; P<.001).
• Each 2-point increase in LCHF score was related to higher % HbA1c (0.010%; 95% CI, 0.004-0.016%; P=.001), whereas each 2-point increase in the DRV score was related to lower % of HbA1c(−0.023%; 95% CI, −0.035 to −0.012%; P<.001).

Limitations

• Risk of residual confounding.