Associations between Vitamin D and β-Cell Function and Colorectal Cancer-Associated Tumor Markers in Chinese Type 2 Diabetic Patients with Albuminuria.

Background: This study is to investigate the protective effects of vitamin D in T2DM, as well as the associations between serum calcifediol level and β-cell function, and risk of CRC, in Chinese type 2 diabetes mellitus (T2DM) patients with albuminuria.

Methods: Serum calcifediol levels were analyzed and compared among healthy individuals and T2DM patients stratified by albumin/creatinine ratio (ACR). Relative correlation analyses were performed with β-cell function (BCF) and risk of CRC.

Results: Patients' ACR was positively associated with fasting plasma glucose and insulin, homeostasis model assessment (HOMA) of insulin resistance (IR), alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA)199, CA125, and Septin9 methylation, but inversely associated with HOMA-BCF and insulin secretion. Serum calcifediol level in the healthy controls was significantly higher than T2DM patients. In T2DM patients, calcifediol level was inversely associated with ACR, HOMA-IR, AFP, CEA, and Septin9 methylation, but positively associated with HOMA-BCF and insulin secretion. Multivariate stepwise principal component regression analysis indicated that calcifediol, hemoglobin A1c, and serum creatinine were independent risk factors for elevated CEA in T2DM.

Conclusions: Higher serum calcifediol level is correlated with better β-cell function, lower insulin resistance, and decreased risk of CRC. Vitamin D may have suppressive effects on T2DM-associated complications and therefore represents a potential prophylactic treatment against β-cell dysfunction and cancer development in T2DM patients with albuminuria.