Chronic low-grade systemic inflammation presented in Type 2 diabetes mellitus plays a major role in disease progression as well as development of micro- and macro-vascular complications of diabetes. Therefore, reducing inflammation can be beneficial in prevention of diabetes complications.

To investigate the association between insulin resistance and inflammatory markers, and assessing the effects of oral Calcitriol on inflammatory cytokines in type 2 diabetic patients.

In this double-blind randomized placebo-controlled trial, 70 participants with type-2 diabetes were randomly divided to two groups. One group received two capsules of Calcitriol (0.25 μg 1,25-dihydroxy cholecalciferol per each capsule) per day. The second group received placebo tablets. At the beginning of the study, we assessed insulin resistance and its relation to inflammatory profile. Serum high sensitive Creactive protein (hs CRP), interleukin-6 and interleukin-18 were also measured at the beginning and the end of the 12-week supplementation trial.

Mean calcium, phosphorus and vitamin D concentrations in the study participants were 8.98 ± 0.79 mg/dl, 3.86 ± 0.50 mg/dl and 40.91 ± 30.9 ng/ml, respectively. IL-18 and hsCRP had significant positive associations with insulin resistance markers and negative associations with insulin sensitivity markers. At the end of the 12-week supplementation trial, no significant difference was seen in serum levels of hsCRP, IL-6 and IL-18 between the two groups, while these values were adjusted for baseline values.

Inflammation was associated with insulin resistance in diabetic patients. No anti-inflammatory effect of Calcitriol in terms of decreasing hsCRP, IL-6 and IL-18 detected.