A systematic review of the prevalence and prognosis of posttransplant diabetes mellitus (PTDM) following the transplantation of heart, lung, liver and kidney and a metaanalysis of randomised studies of glucose-lowering treatment is reported. We searched for publications on solid organ transplants and PTDM in relation to the risk and total mortality of PTDM and randomized controlled trials aiming at reducing glucose levels. PTDM prevalence one year after transplantation was reported to be 9-40%. Ten years after transplantation, 60-85% of people without PTDM and 30-76% of people with PTDM were alive. Following kidney transplantation, we identified six randomized controlled trials on the treatment of PTDM. Intervention ranged from 3 to 12 months. Four studies used intervention with oral glucose-lowering drugs, one used dietician appointments and exercise, and one used insulin treatment. Among the intermediate results reported, a reduction in HbA1c of 2.7 mmol/mol, and an increase in the odds ratio of serious adverse events of 3.0 was significant. In conclusion, information on the prevalence and effect on survival of PTDM is heterogeneous, and the randomized studies on the effect of treatment available are short and lack information on clinically important endpoints, such as mortality or morbidity.