The Sunnybrook Type 2 Diabetes Study

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