Using Early Time Restricted Feeding and Timed Light Therapy to Improve Glycemic Control in Adults With Type 2 Diabetes

Eligibility Criteria

• * Aged 30-80 years old
• * Have type 2 diabetes
• * HbA1c between 5.7 - 12.0%
• * On a stable dose of metformin, DPP-IV inhibitors, SGLT2 inhibitors, sulfonylureas, and/or GLP-1 receptor agonists for at least 6 weeks, or taking no diabetes medications
• * Wake up at a regular time between 5-9 am
• * On insulin or diabetes medication other than metformin, DPP-IV inhibitors, SGLT2 inhibitors, sulfonylureas, and/or GLP-1 receptor agonists
• * Have type 1 diabetes or was diagnosed with diabetes before age 18
• * Moderate or severe retinopathy or other medical condition that may affect the ability to safely receive bright light therapy
• * A history of severe hypoglycemia
• * Change in the dosage of a chronic medication within the past month (need to wait at least 1 month prior to baseline visit)
• * Have a clinically significant laboratory abnormality (e.g., abnormal hemoglobin levels)
• * Severe gastrointestinal disease, major gastrointestinal surgery, or active gallstone disease
• * Cardiovascular, renal, cardiac, liver, lung, adrenal, or nervous system disease that is unstable or may compromise study validity
• * Evidence of cancer (other than non-melanoma skin cancer) within the last 5 years
• * Pregnant or breastfeeding
• * Current diagnosis of a major psychiatric condition that would impair study participation
• * Diagnosed sleep disorder or circadian disorder that is not stabilized (sleep apnea is allowed). Those with narcolepsy will not be included.
• * Major changes in health or medical history in the last 3 months that could affect data validity per judgement of the study physician
• * Spend an average of more than 1.5 hours/day outdoors
• * Perform overnight shift work more than 1 day/week on average
• * Regularly eat within a less than a 10-hour period daily
• * Regularly finish eating dinner before 6:30 pm
• * Lost or gained more than 8 lbs within the last 2 months and weight needs to be stable for a minimum of 4 weeks before baseline testing
• * Traveled more than two times zones away in the two months prior to enrolling in the trial or will travel more than two time zones away during the 16-week study