Sunshine 2 Study for Women With Diabetes

The primary aim of this study is to determine the effect of vitamin D supplementation on depressive symptoms, self-management, and systolic blood pressure compared to placebo. The hypothesis is that women receiving vitamin D supplementation will report fewer depressive symptoms, increased diabetes self- management mediated by depression improvement, and will have a lower systolic blood pressure compared to those taking placebo at three and six months follow-up.

The secondary aim is to explore the mechanistic effect of vitamin D supplementation on inflammatory biomarkers and their association with depression. Here, the hypothesis is that women receiving vitamin D supplementation will have a decrease in inflammatory biomarkers which will be associated with fewer depressive symptoms compared to those taking placebo at three and six months follow-up.

Inclusion criteria

• Women age 21 and older
• Objective evidence of depressive symptoms at the screening and baseline visits
• Diagnosis of type 2 diabetes currently being treated by a healthcare provider
• Blood vitamin D level less than 32 nanograms-per-deciliter (32 ng/dl)

Exclusion criteria

• Current alcohol or substance use disorder
• Any unstable or severe psychiatric disease including diagnoses of schizophrenia, bipolar affective disorder, dementia, delirium, or other psychotic disorder
• Severe complications of diabetes, such as blindness and/or amputation
• Any malabsorption disorder, such as Crohn's disease and/or celiac sprue
• Elevated serum calcium level deemed significant by the Principal Investigator
• Use of 1,000 or more international units daily vitamin D 60 days before enrollment and unwillingness to discontinue vitamin D supplementation 30 days before enrollment.
• Use of St. John's Wort and unwillingness to discontinue St. John's Wort three weeks prior to enrollment.
• Participants who are pregnant, nursing, or planning to become pregnant during the study.
• Baseline systolic blood pressure (SBP) greater than 160 millimeters of mercury (mmHG) or diastolic blood pressure (DBP) greater than 100 mmHG.
• Other serious medical conditions (e.g., cancer, multiple sclerosis, etc.) deemed clinically significant by the Principal Investigator