Low-carbohydrate diet (LCD) has gained interest among individuals with diabetes as a means to manage glycaemia. We investigated the adherence to LCD in the Finnish Diabetic Nephropathy Study and whether carbohydrate restriction is associated with cardio-metabolic risk factors.

Cross-sectional data were available from 902 individuals with type 1 diabetes (44% men, age 47 ± 13 years). Dietary data were collected twice with a 3-day diet record. Mean of the measurements was used. Carbohydrate intake <130 g/day or <26 E% was used as indication of LCD. Individuals reporting LCD were compared to sex-, diabetes duration- and eGFR-matched controls with higher carbohydrate intakes (>253 g/day or >48 E%). In the whole population, carbohydrate-to-fat ratio was calculated and its association with health variables was investigated.

Higher carbohydrate-to-fat ratio was associated with higher blood glucose variability, higher blood pressure, lower HDL cholesterol concentration, and in men with lower waist-to-hip ratio. LCD adherence (n = 69) was associated with lower BMI (25.6 vs. 27.8 kg/m2, p = 0.030), lower variability of blood glucose measurements (0.38 vs. 0.45 mmol/l, p = 0.030), and lower diastolic blood pressure (74 vs. 79 mmHg, p = 0.048). Men reporting LCD had higher total (5.1 vs. 4.0 mmol/l, p = 0.007) and non-HDL cholesterol (3.4 vs. 2.7 mmol/l, p = 0.021). Women with LCD had higher HDL-cholesterol concentration (1.9 vs. 1.5 mmol/l, p = 0.014).

Reduced blood glucose variability, related to LCD, could have clinical relevance to individuals with type 1 diabetes.