INS and type 2 diabetes mellitus: No differences in weight, body mass index, HbA1c, or the results of the OGTT for glucose and insulin were found between groups after the intervention, although a decrease in uric acid was observed in the probiotic group (−0.5 mg/dL; p = 0.037) and a mild increase in HbA1c in the FMT group (+0.25%; p = 0.041); Conclusions: In our sample, neither FMT from healthy and lean donors nor a probiotic were effective in improving insulin sensitivity and HbA1c in patients with T2D.