The Sunnybrook Type 2 Diabetes Study (S2DS) is a prospective observational study of people with prediabetes or Type 2 Diabetes Mellitus (T2DM), that aims to understand the aetiologies, manifestations, and clinical consequences of mood and cognitive complications. The study recruits from the services at Sunnybrook Health Sciences Centre and from the neighbouring University Health Network Toronto Rehabilitation Institute Cardiac Rehabilitation Program.

The S2DS is a prospective observational study of people with prediabetes or T2DM recruited from Sunnybrook Health Sciences Centre and the neighbouring University Health Network Toronto Rehabilitation Institute Cardiac Rehabilitation Program. Participants recruited from Sunnybrook are receiving care from services there (e.g. Family Medicine, Endocrinology, and the Sunnybrook Diabetes Education Centre). Participants recruited from the Toronto Rehab are undertaking a 6-month stepped hybrid (home and clinic based) aerobic plus resistance exercise intervention as part of a program at that site (e.g. the Diabetes, Exercise, and Healthy Lifestyle Program).

Study assessments are conducted at baseline, 3 months, 6 months and 18 months. Main outcomes include cognitive performance, assessed using a detailed neurocognitive battery, and mood symptoms assessed via research criteria for a depressive episode and self-report instruments. Other lifestyle factors are also examined, including physical activity, sleep quality, diet, and subjective stress. Diabetes complications and characteristics are monitored, as are all concomitant medications and supplements. With permission, participant data are linked prospectively to public health records to ascertain long-term outcomes and health services utilization.

The cohort is characterized using biological, neuroimaging and biometric measures. Fasting morning blood and urine samples are taken at each assessment. Serum, plasma, whole blood, and white blood cells are bio-banked for biochemical, genetic and other analyses. The MRI study includes a 1.5 hr MRI scan at 3.0 T. Sequences performed include structural imaging (T1, T2, DTI and FLAIR) and resting state functional MRI. Two optional sub-studies are offered: a cerebrovascular reactivity MRI protocol, and a sleep quality and apnea protocol (baseline, 6 month and 18 month visits). The sleep study uses an overnight wearable sleep monitor.

Inclusion Criteria:

• Have at least one of the following: high HbA1c, impaired fasting glucose (IFG), impaired glucose tolerance (IGT), but not yet diagnosed with Type 2 diabetes or have a diagnosis of Type 2 diabetes.
• Be able to communicate in English
• Be 18 years of age or older

Exclusion Criteria:

• Pregnancy
• Inability to give informed consent
• Current cancer diagnosis
• Have a prior diagnosis of bipolar disorder or schizophrenia.
• Have a prior diagnosis of a neurological and/or neurodegenerative disorder.
• Have a current substance use disorder or a previous substance use disorder diagnosed within the last 5 years (excluding nicotine)
• Poor score on the Mini Mental State Examination (MMSE)

Exclusion criteria (Brain Imaging Sub-Study):

• Contraindications to SHSC's MRI safety protocol.
• Participants that do not meet the inclusion/exclusion criteria of the main study.

Exclusion criteria for (Brain Imaging Sub-Study - CVR procedure):

• Use of medical equipment that would interfere with the placement of the CVR mask.
• Significant pulmonary disease (e.g. asthma, pulmonary fibrosis, emphysema, chronic obstructive pulmonary disease, pulmonary vascular disease, pleural disorders, pneumonia)
• Participants that do not meet the criteria for the MRI sub-study.

Exclusion criteria (Sleep Quality and Apnea Sub-Study):

• Participants that have a medical device that would interfere with placement of portable sleep monitor equipment i.e. Participant requires O2 therapy and uses nasal prongs
• Participants that have a condition that may compromise accuracy of the HSAT results i.e. moderate-severe pulmonary disease or congestive heart failure
• Participants that do not meet the inclusion/exclusion criteria of the main study

The study population consists of individuals with prediabetes or T2DM who are receiving care from an outpatient service at Sunnybrook Health Sciences Centre, or as part of the Diabetes and Healthy Lifestyle Program at the University Health Network Toronto Rehabilitation Institute Cardiac Rehabilitation Program.