IH, Brain Health, and T2D

For 30 patients with documented Type 2 diabetes Inclusion Criteria: * Willing and able to provide written, signed informed consent after the nature of the study has been explained, and prior to any research-related procedures. * Age is \> or = 60 and \< or = 85 years of age * Documented Type 2 diabetes * Scoring 26 or higher on the MoCA test Exclusion criteria: * diagnosis of type 2 diabetes \< 1 year prior to enrollment * HbA1c \<6.5% or \>10.0% * body mass index \> 40 kg/m 2 * incident cardiovascular events in the last year (heart attack, stroke) * symptomatic coronary artery disease and/or heart failure * uncontrolled hypertension * obstructive sleep apnea * pulmonary disease * dementia * renal impairment with creatinine clearance (eGFR) of \<60 ml/min * smoking or history of smoking within past one year 30 nondiabetic control subjects will also be studied. Inclusion criteria: * Willing and able to provide written, signed informed consent after the nature of the study has been explained, and prior to any research-related procedures. * Age is \> or = 60 and \< or = 85 years of age * Scoring 26 or higher on the MoCA test Exclusion criteria: * Diagnosis of diabetes (Type 1 or Type 2) * body mass index \> 40 kg/m2 * incident cardiovascular events in the last year (heart attack, stroke) * symptomatic coronary artery disease and/or heart failure * uncontrolled hypertension * obstructive sleep apnea * pulmonary disease * dementia * renal impairment with creatinine clearance (eGFR) of \<60 ml/min * smoking or history of smoking within past one year