From the article
In the US, approximately 10% of people with prediabetes progress to having diabetes each year.
Intensive lifestyle modification, consisting of calorie restriction, increased physical activity (≥150 min/wk), self-monitoring, and motivational support, decreased the incidence of diabetes by 6.2 cases per 100 person-years during a 3-year period. Metformin decreased the risk of diabetes among individuals with prediabetes by 3.2 cases per 100 person-years during 3 years.
So 6 out of 33 people with lifestyle modification didn't get diabetes over 3 years, while metformin decreased the number by 3 ? And without any intervention about 11 of the 33 would progress to diabetes?
Have I misunderstood the terminology?