Limited scope for vitamin D to prevent type 2 diabetes: study

T2D is characterised by progressive insulin resistance, which is initially compensated by enhanced insulin secretion, but defects may be mitigated with vitamin D intake (associated with reduced T2D risk).

However, where impaired fasting glucose (IFG) is already present, the effect of supplementation may not be strong enough to reverse the damage to glucose metabolism, the authors of a new study in ‘Nutrients’​ say.

“Stratified analysis showed that the effect of low serum 25(OH)D on T2D risk was significant in individuals with baseline FPG lower than 5.6 mmol/L, but not among those with FPG higher than 5.6 mmol/L at baseline,”​ the report states.

Study protocol

Scientists recruited 1,926 adult Chinese subjects to examine the effect of vitamin D on T2D incidence.

Subjects completed questionnaires at baseline to establish demographics, socio-economic status, health parameters, physical fitness, and history of diabetes. There was high prevalence of vitamin D deficiency and high risk of T2D in the study cohort.

They were instructed to continue taking regular medication, except aspirin or non-steroidal anti-inflammatories 48 hours before each visit for data collection.

Blood samples were obtained (following an eight hour overnight fast) for biochemical analysis. Serum 25(OH)D was analysed as a continuous variable or categorical variable and categorised using median thresholds of vitamin D deficiency and insufficiency, quartiles, and quintiles, in relation to three models: serum 25(OH)D as the independent variable (model 1); serum 25(OH)D with age, gender, and BMI variables (model 2), and serum 25(OH)D with all remaining socio-demographic parameters (model 3).