Objective  To explore value of serum Mac-2 binding proteoglycan isomer(M2BPGi) in diagnosing liver fibrosis in patients with type 2 diabetes mellitus(T2DM).

  Methods  A total of 272 patients diagnosed as T2DM were recruited as study objects, and were divided into T2DM combined with NAFLD group with 122 patientsnon-alcoholic fatty liver disease (NAFLD)and T2DM group150 T2DM patients without NAFLD. In addition, serum samples from 150 healthy volunteers(normal control group) who underwent physical examinations in our hospital at the same time were collected as normal controls. According to different NAFLD fibrosis scores, T2DM patients combined with NAFLD were divided into liver fibrosis free subgroup (n=44), uncertain subgroup (n=42), and liver fibrosis subgroup (n=36). Chemiluminescence enzyme immunoassay was used to analyze the level of serum M2BPGi. The levels of laboratory examination indexes in each group were compared. Spearman rank correlation test was used to analyze the correlations of all indicators, and receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of serum M2BPGi for NAFLD in T2DM patients and for liver fibrosis of T2DM patients with NAFLD.

  Results  The serum M2BPGi in the T2DM combined with NAFLD group was significantly higher than that in the T2DM group and normal control group (P < 0.001). The area under the curve (AUC) of serum M2BPGi in diagnosis of T2DM combined with NAFLD was 0.919 (95%CI, 0.885 to 0.954). Four indicators of liver fibrosishyaluronic acid (HA), laminin (LN), procollagen type Ⅲ (PC-Ⅲ) and collagen type Ⅳ (Ⅳ-C)and serum M2BPGi levels in the liver fibrosis subgroup were higher than those in the liver fibrosis free subgroup and the uncertain subgroup, and the above indicators of the uncertain subgroup were higher than those of the liver fibrosis free subgroup, the differences were statistically significant (P < 0.05). ROC curve analysis showed that AUC of serum M2BPGi in diagnosis of liver fibrosis in T2DM patients with NAFLD was 0.993 (95%CI, 0.983 to 1.000), which was higher than the value for AUC diagnosed by HA, LN, PC Ⅲ or Ⅳ-C alone. Serum M2BPGi levels of patients with T2DM and NAFLD were positively correlated with HA, LN, PC Ⅲ and Ⅳ-C (r=0.741, 0.835, 0.851, 0.867, P < 0.05).

  Conclusion  The level of serum M2BPGi in T2DM patients with NAFLD are generally elevated, and its level is associated with progression of liver fibrosis. M2BPGi is expected to be a novel marker for evaluating the progression of liver fibrosis in patients with T2DM complicated with NAFLD.