No association of 25-hydroxyvitamin D and parathormone levels with glucose homeostasis in type 2 diabetes - a study from Shillong, Meghalaya.

BACKGROUND: Although inadequate vitamin D and altered parathyroid hormone (PTH) are implicated in deranged glucose metabolism and risk of future diabetes, their role in regulating glucose homeostasis in established cases of diabetes is unclear. We aimed to (i) evaluate vitamin D status, and (ii) determine if vitamin D and PTH were associated with parameters of glucose homeostasis in type 2 diabetes (T2D) patients from Meghalaya, India.

METHODS: We determined 25-hydroxyvitamin D (25-OH-D) and PTH concentrations in 251 T2D patients (not on insulin), and examined their associations with the following parameters of glucose homeostasis: fasting blood sugar (FBS), post-prandial blood sugar (PPBS), glycated hemoglobin (HbA1c), fasting insulin (FI), homeostasis model assessments of insulin resistance (HOMA-IR) and β-cell function (HOMA-β).

RESULTS: None of the patients had adequate vitamin D (mean 25-OH-D = 19.3 ng/mL); 47.8% patients were deficient (25-OH-D < 20 ng/mL), while 52.2% were insufficient (25-OH-D < 30 ng/mL) vitamin D. Significant ( P < 0.05) univariate associations were observed between: 25-OH-D and FI ( r = 0.14); 25-OH-D and HOMA-β ( r = 0.13); PTH and FI ( r = -0.18), and PTH and HOMA-β ( r = -0.11). However these associations disappeared after controlling for potential confounders. The 25-OH-D and PTH levels were not associated with any of the tested parameters of glucose homeostasis.

CONCLUSION: There was widespread prevalence of vitamin D deficiency/insufficiency in our sample T2D patients. However, neither vitamin D nor PTH appeared to play a major role in influencing glucose homeostasis in this present selection of T2D cases.