Type 2 diabetes (T2D) will affect \ 650 million adults worldwide by 2040 and about as many will have pre-diabetes. Chronic hyperinsulinemia/insulin resistance precedes T2D development. Studies link insulin resistance with chronic inflammation and oxidative stress. In Guinea-Bissau, a low-income country in West Africa, the T2D incidence is largely unknown and there is an acute lack of diabetes doctors, nurses and other diabetes educators. They hardly have access to insulin, and mortality from T2D complications is high. Previous studies by the Bandim Health Project (www.bandim.org) in the country show that the Bacillus Calmette-Guérin (BCG) vaccine has non-specific effects, well beyond tuberculosis prevention, conferring a general protection against unrelated pathogens. At the same time, studies from the US have also shown that BCG can significantly improve glycemic control in Type-1 diabetes (T1D) patients. Yet, no such studies have been done in T2D or pre-diabetes. The purpose of the present study is to administer BCG to patients with pre-diabetes, in order to reduce hyperinsulinemia/chronic inflammation, a novel strategy to flatten the growing T2D incidence.