Objective       To investigate the effect of metformin on the heart function of patients having type 2 diabetes mellitus complicated with diastolic heart failure.       Methods       The study

adopted a single-center

randomized

double-blind and prospective design

and a total of 170 patients with type 2 diabetes mellitus complicated with diastolic heart failure were randomized into an experimental group and a control group. Patients in the control group were given conventional treatment

and those in the experimental group were given metformin (1 000 mg/d) combined with conventional treatment. Six-min walk distance (6-MWT)

peak early filling velocity to peak late filling velocity (E/A)

E-wave deceleration time (DT)

left ventricular mass index (LVMI)

N-terminal pro-brain natriuretic peptide (NT-proBNP) and growth differentiation factor-15 (GDF-15) were determined at baseline and at 3

6

9

and 12 months of treatment.       Results       The follow-up at 12 months showed that a total of 12 cases were lost and 158 cases had complete data

including 80 cases in the experimental group and 78 cases in the control group. 6-MWT increased and NT-proBNP decreased significantly in the two groups after 3 months of treatment compared with those at baseline (

P

<

0.05). E/A and DT decreased significantly (

P

<

0.05) at 9 months in the control group and at 6 months in the experimental group. Compared with the control group

6-MWT increased significantly in the experimental group after 6 months of treatment

and E/A

DT

and NT-proBNP decreased significantly after treatment for 9 months (

P

<

0.05). LVMI and GDF-15 decreased significantly in the control group after 9 months of treatment compared with those at baseline

whereas LVMI and GDF-15 in the experimental group decreased markedly after treatment for 6 months and 3 months

respectively (

P

<

0.05). Compared with the control group

the experimental group showed LVMI significantly decreased at 12-month follow-up (

P

<

0.05) and sharp decline of GDF-15 after treatment for 6 months (

P

<

0.05).       Conclusion       Metformin can improve the heart function of type 2 diabetes patients complicated with diastolic

heart failure by increasing diastolic filling volume and improving left ventricular remodeling.