Associations of dietary macronutrient and fibre intake with glycaemia in individuals with Type 1 diabetes

Aims To study the association between dietary intake and glycaemia in Type 1 diabetes. Methods Data on energy and nutrient intakes, and the mean and coefficient of variation of self-monitored blood glucose measurements were obtained from records completed by 1000 adults with Type 1 diabetes. Associations between these measures of glycaemia and dietary intake were investigated using generalized linear regression, with and without macronutrient substitution. Results In the first set of analyses, fibre intake was associated with lower mean self-monitored blood glucose values (beta = -0.428, 95% CI -0.624 to -0.231; P<0.001). In these same analyses, carbohydrate (beta = 0.011, 95% CI 0.002 to 0.020; P=0.014), alcohol (beta = 0.013, 95% CI 0.003 to 0.023; P=0.009) and monounsaturated fatty acid intakes (beta=0.012, 95% CI 0.001 to 0.023; P=0.029) were associated with higher variability in blood glucose measurements. In the macronutrient substitution analyses, substituting proteins for either carbohydrates (beta = -0.026, 95% CI -0.040 to -0.013; P<0.001), fats (beta = -0.018, 95% CI -0.033 to -0.004; P=0.014), or alcohol (beta = -0.026, 95% CI -0.045 to -0.006; P=0.010), or fats for carbohydrates (beta=-0.009, 95% CI -0.017 to -0.001; P=0.030), were all associated with lower variability in the measured blood glucose values. After adjusting for fibre intake, no significant results were observed in analyses of mean self-monitored blood glucose. Conclusions This observational, cross-sectional study indicates that dietary fibre is associated with lower mean blood glucose concentrations in people with Type 1 diabetes. Glycaemic excursions were reduced when protein was substituted for other macronutrients and when fat replaced carbohydrate, after adjusting for fibre intake.