Taking data from the 2009 — 2010 Victoria Health Monitor survey, the study analysed 3,393 Australian subjects between the ages of 18 and 75 in Victoria, and found that vitamin D status was inversely proportional to risk markers for type 2 diabetes.
The data consisted of physical activity, dietary behaviour, and biomedical information, and subjects had their blood samples collected after an overnight fast of at least 10 hours. The blood samples were analysed for fasting plasma glucose, glycated haemoglobin, vitamin D, triglycerides, and HDL cholesterol. The subjects’ blood pressure, height, weight, and waist circumference were also recorded.
Additionally, the study “adjusted for the following socio-demographic factors: age, gender, country of birth, and Index of Relative Socio-economic Disadvantage (IRSED), physical activity, smoking status, and season”.
Subjects who had higher levels of vitamin D had their risk of fasting plasma glucose and glycated haemoglobin lowered by 39% and 26% respectively. This was the case even after the researchers adjusted for several socio-demographic, dietary, and biomedical variables, as well as metabolic syndrome factors such as dyslipidemia, hypertension and obesity, which are common in pre-diabetic patients.
Furthermore, it was likely vitmain D's effect on insulin action that led to a lower risk of type 2 diabetes. Vitamin D is vital to beta cell function and insulin secretion, both of which are affected by vitamin D deficiency. Vitamin D has also been shown to consistently reduce low-grade chronic inflammation, which might precede type 2 diabetes.
Vitamin D deficiency is prevalent in many countries, with China and India among the most vitamin D-deficient, and Australia not far behind. Approximately 31% of the population have insufficient vitamin D levels, especially older Australians.
At the same time, the global “prevalence of type 2 diabetes mellitus has also risen tremendously in the last 10 years, with projections that countries like India and China will have the highest numbers by 2030, at 79.4 and 42.3 million respectively”.
The study also stated that genetics have a part to play in type 2 diabetes and vitamin D levels, saying that family history of the disease could increase the risk of its development in later generations, and that vitamin D levels “may vary due to the genetic variation of three polymorphisms in the vitamin D genes”.
It concluded that the association of higher vitamin D status with lower prevalent fasting plasma glucose and glycated haemoglobin concentrations “could suggest a direct role for the vitamin in the prevention" of type 2 diabetes.
Source: PLOS ONE
“Vitamin D status is inversely associated with markers of risk for type 2 diabetes: A population based study in Victoria, Australia”
Authors: Poonam K. Pannu, et al.