Association of serum undercarboxylated osteocalcin with diabetic retinopathy in male patients with type 2 diabetes mellitus

Objective To investigate the relationship between the level of serum undercarboxylated osteocalcin (ucOC) with the development and progression of diabetic retinopathy (DR) in male patients with type 2 diabetes mellitus (T2DM). Methods A total of 125 male patients with T2DM cared at Tangshan Gongren Hospital from October 2015 to November 2016 were recruited as subjects, they were divided into three groups as: T2DM without DR group (NDR, n=45), T2DM none-proliferative DR group (NPDR, n=42) and T2DM with proliferative DR group (PDR, n=38). 50 male subjects without T2DM from the medical examination center were selected as normal control group (NC). Data including age, diabetes duration, body mass index, systolic blood pressure, diastolic blood pressure were recorded, and clinical biochemical indicators including fasting plasma glucose, glycated hemoglobin A1c, triglyceride, total cholesterol, low-density lipoprotein-cholestrol, high-density lipoprotein-cholestrol (HDL-C), 24 h urinary albumin excretion rate (UAER) and fasting insulin were collected, homeostasis model assessment of insulin resistance (HOMA-IR) was calculated, ucOC was measured by enzyme linked immunosorbent assay. Multiple-group comparisons were analyzed by one-way ANOVA or Kruskal-Wallis H test. Two-group comparisons were analyzed by LSD test or LSD test by rank conversion. Multivariate correlation analysis was used Pearson or Spearman correlation analysis. Risk factor screening was used multiple stepwise regression analysis. Results (1) The serum ucOC level of T2DM groups were lower than NC group. The order of serum ucOC level from low to high were PDR, NPDR, NDR and NC [(1.4±0.6), (2.1±0.9), (2.7±0.9), (3.3±0.9) μg/L, F=63.149, all P<0.05]. (2) Serum ucOC was negatively associated with HbA1c, HOMA-IR, 24hUAER (r=-0.379,-0.237,-0.429, all P<0.05), and was positively associated with HDL-C (r=0.223, P<0.05). (3) Logistic regression analysis showed that duration of diabetes, HOMA-IR, 24hUAER and ucOC were independent risk factors of DR in male T2DM patients (OR=0.396-2.523, all P<0.05). Conclusion The reduction of serum ucOC in male T2DM patients may be related to the development and progression of DR. Key words: Diabetes mellitus, type 2; Male; Diabetic retinopathy; Undercarboxylated osteocalcin