Recruitment for phase 1 is completed, waiting for phase 2

Type 1 diabetes mellitus (T1D) is the most common form of diabetes among children and youth, and it is increasing around the world, particularly among children under 5 years. This is worrisome given the chronic nature of the disease and its strong association with an increased risk of cardiovascular disease (CVD). Evidence suggests that markers of CVD are already present in children with T1D, making prevention a clinical and public health priority in this high-risk population. Despite this, a good understanding of what factors predispose children with T1D to CVD is still lacking.

Our study aims to better understand in this population what individual, familial and environmental characteristics increase the risk for heart disease, how to best measure it early on and what are the potential mechanisms underlying the heightened risk for heart disease in youth with T1D. Specifically, we aim to:

1. compare established risk factors (dyslipidemia, hypertension) with novel early markers for CVD (cardiac phenotype, arterial stiffness, endothelial function) in adolescents with T1D and healthy controls;
2. examine the associations between these novel early markers with: i) lifestyle habits; ii) measures of inflammation; and iii) markers of oxidative stress among adolescents with T1D and healthy controls, and determine group differences in these associations;
3. explore, across both groups, the associations between these established and novel early markers of CVD with neighborhood features.
4. Determine sex and gender differences in novel markers of CVD (cardiac structure/myocardial oxygenation, vascular studies including endothelial function and arterial stiffness) in youth with T1D and healthy controls;
5. Determine, across both groups, sex and gender differences in associations between markers of CVD and lifestyle habits, specifically: i) moderate-to-vigorous physical activity (MVPA); ii) dietary intake (carbohydrates, sugar, saturated/trans-fat, fiber, food groups); iii) sedentary behavior; and iv) sleep;
6. Measure changes in novel markers of CVD from adolescence to early adulthood among individuals with T1D and healthy controls;
7. Assess whether lifestyle habits in adolescence are prospectively associated with established (dyslipidemia, hypertension) and novel (cardiac structure/myocardial oxygenation, endothelial function, arterial stiffness) markers of CVD in early adulthood, and if these associations differ according to T1D status, adiposity, sex and gender.

To achieve these objectives, we will compare 300 participants aged 14-18 years with T1D to 300 healthy controls. 100 participants from each group will be reassessed at the age of 22-26 yo. Lifestyle habits include assessments of physical activity, sleep, sedentary behavior, fitness and dietary intake. Blood pressure and lipid profiles will be measured. Cardiac structure/function will be evaluated by non-contrast cardiac magnetic resonance imaging (CMR). Aortic distensibility will be determined by pulse wave velocity. Endothelial function will be determined by flow-mediated dilation. Inflammatory markers and endogenous antioxidants will be measured in blood. Intestinal microbiota will be assessed. Neighbourhood features include built and social environment indicators and air quality.

Our study provides an exceptional opportunity to increase our knowledge on what factors predispose children with T1D to cardiovascular disease. Understanding the interplay between T1D, lifestyle habits and metabolic markers and CVD is critical to developing effective prevention strategies for these vulnerable children.

Inclusion Criteria:

• Diagnosis of T1D (for the T1D group) or no diagnosis of any type of diabetes (for the control group)
• 14 to 18 years old

Exclusion Criteria:

• Youth with another type of diabetes such as T2D
• Conditions that could limit their ability to participate in the study
• Known pathology that would influence their risk for CVD
• Siblings of a participant already enrolled in the study

T1D group: Sainte-Justine Hospital's Diabetes Clinic patients

Control group: Community sample