Vitamin D levels and other factors associated with depressive symptoms and cognitive impairment in the oldest-old patients with diabetes

The aim of the study was to determine the serum 25-hydroxvitamin D levels in patients aged over 85 years with type 2 diabetes and identify the factors (including vitamin D levels) associated with comorbid depressive symptoms and mild cognitive impairment (MCI). A group of 188 T2D patients aged 85 or older was screened with the 30-item Geriatric Depression Scale (GDS-30) and the Montreal Cognitive Assessment (MoCA). Biochemical and biomarker data were collected. Among the participants, 13.3% had depressive symptoms, 27.6% had MCI and 20.2% had both. The latter group were significantly more likely to have the following characteristics compared to controls: female, single, smoker, older, less physically active, lower level of education, higher number of co-morbidities, retinopathy, cardiovascular diseases, hyperlipidemia, longer duration of diabetes, higher levels of HbA1c, triglycerides, BMI and GDS score, lower concentrations of HDL and MoCA score. The lowest concentration of serum 25-hydroxvitamin D was found in diabetics with comorbid depressive symptoms and MCI; this value negatively correlated with HbA1c concentration and GDS-30 score, and positively correlated with MoCA score. Vitamin D is associated with depressive symptoms and cognitive dysfunction in patients aged over 85 years with type 2 diabetes.