VITAMIN B12 DEFICIENCY IN METFORMIN-TREATED COMMUNITY-DWELLING OLDER ADULTS WITH DIABETES: A CROSS-SECTIONAL MULTICENTRE STUDY IN PERAK Introduction: Surveillance studies have shown a high prevalence of vitamin B12 deficiency in metformin-treated adults. Community-dwelling older adults have a higher risk of vitamin B12 deficiency due to lower gut absorption. To date, data on this specific cohort are lacking. We aimed to investigate the local prevalence of vitamin B12 deficiency and its associated factors among metformin-treated older adults. Methods: This prospective cross-sectional study investigated community-dwelling patients with diabetes aged ≥65 years from four healthcare facilities from August 2023 to March 2024. Blood samples were sent to a central laboratory to determine vitamin B12 levels. Vitamin B12 deficiency was defined as serum vitamin B12 levels of ≤221 pmol/L. Descriptive analysis, chi-square test (or Fisher’s exact test) and independent t-test (or Mann–Whitney U test) were performed. Results: One hundred two participants were included in the study, of whom 61.8% were women (n=63), and 55.9% were Malays (n=57). The median age was 70 years (interquartile range [IQR]=67–74), and the median duration of metformin usage was 9.0 years (IQR=5.0–12.3). The prevalence of vitamin B12 deficiency was 29.4% (95% confidence interval [CI]=20.4–38.4, n=30), with a median vitamin B12 level of 287.0 pmol/L (IQR=200.5–448.8). Vitamin B12 deficiency was significantly associated with advancing age (P<0.05), but not with sex, ethnicity, duration of diabetes, metformin use, BMI, latest HbA1c level recorded and haemoglobin level (P>0.05). Conclusion: Patients with diabetes aged ≥65 years have a high prevalence of vitamin B12 deficiency. Blood screening for vitamin B12 deficiency is needed for this population in Peninsular Malaysia.