Abstract
Introduction and aim Vitamin D deficiency and insufficiency are widely recognized as significant concerns among individuals with type 2 diabetes mellitus (T2DM). Adequate sunlight exposure is essential for synthesizing vitamin D, yet Malaysia, despite its tropical climate, faces a high prevalence of vitamin D deficiency and insufficiency. This study aimed to determine the prevalence of vitamin D deficiency and insufficiency and their relationship with sun exposure among T2DM patients in Southern Malaysia. Methodology A cross-sectional study was conducted among 330 T2DM patients in Johor, a southern region of Malaysia. A blood sample of 3 mL was collected from each respondent for serum vitamin D analysis. Respondents must fast for at least 8 hours before taking the blood sample. Serum vitamin D levels were analyzed via ultra-performance liquid chromatography (UPLC) at the Universiti Kebangsaan Malaysia (UKM) Medical Molecular Biology Institute (UMBI). A validated questionnaire was used to collect data on the duration of sunlight exposure on weekdays and weekends. Results Multinomial logistic regression analyses were used to determine the factors associated with vitamin D deficiency and insufficiency. The mean serum vitamin D level was 49.26 (SD 15.21) nmol/L. A total of 12.1% (n=40) of the respondents were classified as vitamin D deficient and 46.4% (n=153) as vitamin D insufficient. The analysis showed that the patients with sun exposure ≤30 minutes during weekdays were significantly more likely at higher risk of vitamin D insufficiency (adjusted odds ratio {AOR}: 2.28, 95% CI: 1.09-4.88) and vitamin D deficiency (AOR: 4.12, 95% CI: 1.02-6.64). A similar trend was observed on weekends. Patients with sun exposure ≤30 minutes had higher odds of having vitamin D insufficiency (AOR: 3.82, 95% CI: 1.14-2.85) and vitamin D deficiency (AOR: 4.26, 95% CI: 1.14-2.85). Conclusion Vitamin D deficiency and insufficiency are common among individuals with type 2 diabetes mellitus (T2DM) in Johor, with limited sun exposure identified as a significant modifiable risk factor. Addressing this issue necessitates targeted public health initiatives to enhance awareness and promote appropriate sun exposure practices, ultimately aiming to improve vitamin D status and health outcomes in this vulnerable population.