Characteristics of study participants are shown in . Study participants with type 1 diabetes were significantly younger than participants without diabetes, both among men and women. Only 18% of men and 22% of women met the ADA's goal of a HbA1c <7%. Men with type 1 diabetes had less intra-abdominal fat (IAF), a smaller average waist circumference, lower total and LDL-cholesterol, lower triacylglycerol, and higher HDL-cholesterol than men without diabetes. Similarly, women with type 1 diabetes had less IAF, lower total and LDL-cholesterol, lower triacylglycerol and higher HDL-cholesterol than women without diabetes. Physical activity levels did not differ by diabetes status among either men or women, but AER and CAC were significantly increased among participants with type 1 diabetes.
Characteristics of Study Participants by Gender and Diabetes Status
Daily intake in kilocalories per kg body weight did not differ in men by diabetes status, but women without diabetes reported a higher daily intake of kilocalories per kg body weight than women with type 1 diabetes. However, both men and women with type 1 diabetes reported consuming less of their daily calories as carbohydrate (CHO), and more as fat and protein than non-diabetic individuals. In addition, saturated fat intake as a percentage of daily calories was significantly higher in both men and women with type 1 diabetes than in men and women without diabetes. Glycaemic index (GI), which is the ratio of a food's influence on blood sugar levels (2 hour glucose area under the curve) compared to glucose and multiplied by 100, was similar in all groups. However, glycaemic load, which is the carbohydrate content in grams multiplied by the GI and then divided by 100, was significantly lower in both men and women with type 1 diabetes compared to control men and women.
shows adherence to dietary guidelines (ADA, AHA, and DRI) in the cohort, by diabetes and gender. Significantly fewer individuals with type 1 diabetes met the DRI goal for total fat intake (20-35% of daily intake) than controls, and fewer people with type 1 diabetes met the goal for saturated fat intake of < 10% of daily calories. Fewer adults with type 1 diabetes than controls met the goal of obtaining 45-65% of daily caloric intake from CHO, but nearly all participants met the recommended goals for protein intake (10-35% of daily intake). Adherence to guidelines for intake of folate, Vitamin E calcium and fiber did not differ by diabetes status. All women met the daily recommended intake of Vitamin C, while control men had significantly lower adherence to Vitamin C guidelines than men with type 1 diabetes. Less than half of study participants met calcium guidelines, with calcium intake lowest among control men and significantly lower than in men with type 1 diabetes. Fiber intake did not differ by diabetes status, but only 6% of men in both groups met fiber guidelines, while 30% of women with type 1 diabetes and 31% of women without diabetes met the fiber guidelines.
Percentage of study participants meeting dietary goals for macro- and micro-nutrients by gender and diabetes status (white bars: Male T1D; light gray bars: Male non-diabetic; dark gray bars: Female T1D; black bars: Female non-diabetic)
We then examined whether the dietary composition was correlated with CHD risk factors, including total cholesterol, LDL- and HDL-cholesterol, triacylglycerol, non-HDL cholesterol, Apolipoprotein B, HbA1c, BMI, IAF volume, waist circumference and EGDR. As shown in , the percentage of calories from fat, the percentage of calories from saturated fat, and the percentage of calories from monounsaturated fatty acids (MUFA) were all significantly positively correlated with total and LDL-cholesterol, non-HDL cholesterol, Apolipoprotein-B, HbA1c, BMI, IAF, waist circumference and DBP, and negatively correlated with EGDR. The percentage of calories from trans fat and the percentage of calories from polyunsaturated fatty acids (PUFA) were also significantly positively correlated with LDL-cholesterol, non-HDL cholesterol, Apolipoprotein-B, BMI, IAF, waist circumference, and DBP, and negatively correlated with EGDR. A higher average dietary glycaemic index was associated with lower HDL-cholesterol and EGDR, and higher triacylglycerol, non-HDL cholesterol, Apolipoprotein-B, IAF, SBP and DBP. On the other hand, increased carbohydrate intake was significantly negatively correlated with total, LDL- and HDL-cholesterol, non-HDL cholesterol, Apolipoprotein-B, HbA1c, BMI, IAF, waist circumference and DBP, and significantly positively associated with EGDR.
Pearson Partial Correlation Coefficients for Dietary % Intake of Fats and Carbohydrates, Adjusted for Age, Sex, calories per day and type 1 diabetes
Univariate associations between variables of interest and CAC were explored (), and all covariates were significantly associated with the presence of CAC except for intake of protein and glycaemic index. The relationship between dietary composition and presence of CAC was then examined in logistic regression models, shown in . Model 1 was adjusted for age, sex, total kcal intake per day and diabetes status, and interaction terms for diabetes status and each dietary variable were included but non-significant (p>0.10) and therefore were dropped. A high fat diet (>35% fat), saturated fat as a percentage of calories, and protein intake as a percentage of calories were associated with increased odds of CAC when adjusted for Model 1, and when further adjusted for triacylglycerol and HbA1c. Protein intake remained associated with the presence of CAC when adjustment was made for HDL- and LDL-cholesterol, hypertension, physical activity, and EGDR, and a high fat diet remained significantly associated with CAC when adjusted for HbA1c and AER. The percentage of calories from carbohydrate was associated with decreased odds of CAC when adjusted for Model 1 (age, sex, total kcal intake per day, diabetes status), and remained significantly associated with reduced odds of CAC when further adjusted for lipids, hypertension, physical activity, HbA1c, and AER. Associations between high fat diet, saturated fat, carbohydrate and protein intake and CAC were all attenuated when adjustment was made for BMI. Glycaemic index was not associated with CAC in any of the models. A fully adjusted model (excluding EGDR and non-HDL cholesterol as these variables are a linear combination of other variables) revealed that the relationships between dietary variables and CAC were not significant when adjusted for all other variables of interest.
Univariate associations of covariates with coronary artery calcium
Odds Ratios and 95% Confidence intervals for Association of Dietary Macronutrients and Coronary Artery Calcium
Finally, in order to explore inter-relationships between dietary components, a forward selection logistic regression model was fitted, with age, diabetes status, high fat diet, protein intake, carbohydrate intake, and glycaemic index forced into the model (Model 5). Additional variables which entered the model were triacylglycerol, BMI, and EGDR, and an interaction term for protein intake and diabetes status. Protein intake was significantly associated with presence of CAC only among participants with type 1 diabetes when adjusted for other dietary variables.