Maintaining adequate vitamin D levels may play an important role in healthy ageing among people with type 2 diabetes (T2D). A new study published in Scientific Reports found that adults aged 85 years and older with T2D who had both depressive symptoms and mild cognitive impairment (MCI) exhibited the lowest serum vitamin D concentrations compared with those without these conditions. The cross-sectional study evaluated 188 older adults using standardized neuropsychological assessments and blood measurements of 25-hydroxyvitamin D [25(OH)D]. Researchers observed that lower vitamin D levels were strongly associated with poorer cognitive performance, more severe depressive symptoms, higher HbA1c levels, longer duration of diabetes, and greater overall disease burden.

      After adjusting for demographic and clinical factors, lower serum vitamin D remained independently associated with the combined presence of depression and MCI, with each 1 ng/mL increase in vitamin D linked to approximately a 23% lower likelihood of having both conditions. However, the authors emphasize that this observational study demonstrates an association rather than causation, and the findings do not support routine vitamin D supplementation as a treatment for cognitive decline or depression. Larger prospective studies and randomized clinical trials are needed to determine whether improving vitamin D status can positively influence cognitive and mental health outcomes in older adults with diabetes. These findings nevertheless highlight the importance of comprehensive geriatric assessment, including nutritional status, in the management of the oldest-old living with T2D.