ALB and diabetic kidney disease: The urinary albumin/urinary creatinine ratios at 1 month (6 studies included) and at 2 months (10 studies included) were observed to be significantly lower in the MSC-treated group than in the untreated DKD group (1 month: SMD = − 2.419, 95%CI − 3.070 to − 1.769, p < 0.001; I2 = 0.0%; 2months: SMD = − 2.648, 95%CI − 3.454 to − 1.842, p < 0.001; I2 = 58.9%).