Aim: To determine the prevalence of vitamin D insufficiency in Asian patients with type 2 diabetes and to determine the most appropriate screening investigations.
Introduction: The high prevalence of vitamin D deficiency and type 2 diabetes in the Asian community is well recognised. Vitamin D insufficiency (levels < 50 nmol/l) is associated with impaired insulin secretion and increased insulin resistance. The prevalence of Vitamin D insufficiency in patients with diabetes is not well characterised.
Patients and Methods: 170 Asian diabetic patients were screened together with 27 control subjects who were identified either from a local mosque or were relatives of patients attending the diabetes centre. All were over 40 years of age and none were taking calcium or vitamin-D supplements. Vitamin D, serum parathyroid hormone, standard bone profile (serum calcium, phosphate, alkaline-phosphatase) and serum creatinine were measured.
Results: In the diabetes cohort Vitamin-D levels were significantly lower (34.0±22.9 Vs 45.4±25.7; P<0.02) and a higher proportion had Vitamin D insufficiency (83% v 60%; P=0.01). There was no significant difference in serum parathyroid hormone levels (58.9±63.2 v 59.0±30.8; P=0.1) although 20% of the diabetic cohort still had secondary hyperparathyroidism. Of 129 diabetic patients with vitamin D insufficiency, only 6 (4.7%) had abnormal standard bone profile.This confirms that a standard bone profile is an inadequate screening test for Vitamin D insufficiency.
Conclusion: Vitamin D insufficiency is even more common in Asian diabetic patients than controls. This is worrying given the known effect of vitamin D insufficiency on insulin secretion and insulin resistance. Screening for Vitamin D insufficiency in this group of patients should be routine and is best achieved by measuring 25-OH-Vitamin D levels and serum Parathyroid hormone.