Abstract: Objective To investigate the expression of alkaline phosphatase (TNAP) in patients with type 2 diabetes mellitus (T2DM) and its mechanism of regulating uncoupling protein 1 (UCP1) / Irisin in adipocytes. 
Methods A cohort study was performed on 80 outpatients and inpatients with T2DM in the First Central Hospital of Baoding City, and 80 healthy volunteers were collected as controls. The expression levels of serum TNAP and energy metabolism molecules UCP1 and Irisin in the two groups were detected by enzyme linked immunosorbent assay （ELISA）. In terms of cytological test, 3T3-L1 adipocytes were divided into three groups: control group, NC group (transfected with NC plasmid) and experimental group (transfected with Si TNAP plasmid), and 3T3-L1 adipogenic differentiation was induced. The adipogenic differentiation ability of cells in each group was detected by oil red O staining, and the glucose consumption level and triglyceride consumption level of cells in each group were detected. The expression levels of energy metabolism pathway molecule UCP1 and Irisin mRNA were detected by qPCR, and the protein expression levels of UCP1 and Irisin were detected by Western blot. 
Results For cohort study, compared with the control group, the expression level of serum TNAP in the experimental group increased, while the expression levels of UCP1 and Irisin decreased significantly (P＜0.01). Cytological test showed that compared with the control group, the adipogenic capacity of cells in the experimental group increased, and glucose consumption and triglyceride production increased significantly (P＜0.01). qPCR results showed that compared with the control group, the expression levels of UCP1 and Irisin mRNA in the experimental group increased (P＜0.01), and Western blot results showed that the expression levels of UCP1 and Irisin protein in the experimental group increased (P＜0.01). 
Conclusion TNAP may affect the energy metabolism of adipocytes by inhibiting the energy metabolism pathway UCP1/Irisin, and participate in the occurrence and development of T2DM.

Key words: diabetes, type 2, energy metabolism, adipocytes