Calcification biomarkers and vascular dysfunction in obesity and type 2 diabetes: influence of oral hypoglycemic agents.

Abstract

Vascular aging in obesity and type 2 diabetes (T2D) is associated with progressive vascular calcification, an independent predictor of morbidity and mortality. Pathways for vascular calcification modulate inhibition of bone matrix deposition thus regulating calcium deposits. We investigated the association between biomarkers of vascular calcification and vasodilator function in obesity or T2D, and whether antidiabetic therapies favorably impact those markers. Circulating levels of proteins involved in vascular calcification, such as osteopontin (OPN), osteoprotegerin (OPG), regulated on activation, normal T cell expressed and secreted (RANTES), and fetuin-A were measured in lean subjects, individuals with metabolically healthy obesity (MHO) and patients with metabolically unhealthy obesity (MUO) or T2D. Vasodilator function was assessed by infusion of acetylcholine (ACh) and sodium nitroprusside (SNP). Circulating levels of OPN were higher in the MUO/T2D group than in lean subjects (P<0.05); OPG and RANTES were higher in MUO/T2D group than in the other groups (both P<0.001); fetuin-A was not different between groups (P>0.05); vasodilator responses to both ACh and SNP were impaired in both MUO/T2D and MHO compared to lean subjects (both P<0.001). In patients with T2D enrolled in the intervention trial, antidiabetic treatment with either glyburide, metformin or pioglitazone resulted in significant reduction of circulating OPG (P=0.001), without changes in the other biomarkers and vasodilator responses (all P>0.05). In conclusion, obese patients with MUO/T2D have elevated circulating OPN, OPG and RANTES; in these patients, antidiabetic treatment reduces only circulating OPG. Further study is needed to better understand the mechanisms of vascular calcifications in obesity and diabetes.