We report the functional cure of an elderly type 2 diabetes (T2D) patient by intravenous transplantations of mesenchymal stem cells derived from Wharton’s jelly portion of human umbilical cord (UCWJ-MSCs) double overexpressing human estrogen-related receptor γ (ERRγ) and insulin genes. After 40 times of systemic infusions, the patient’s antidiabetic drugs (3 tablets of Acarbose and 3 tablets of Metformin daily) and exogenous insulin injections (47 IU daily) were completely replaced. More importantly, the patient’s T2D-derived microvascular and macrovascular complications were repaired and improved significantly during and after transplantations. Our data provides a proof of principle for human stem cell-gene therapy to treat human diabetes. As we invented and applied this protocol to treat human diabetes in China, we designated this method as “China Protocol”.