About 90–95% of all North American cases of diabetes are type 2, and about 20% of the population over the age of 65 has diabetes mellitus type 2. The fraction of type 2 diabetics in other parts of the world varies substantially, almost certainly for environmental and lifestyle reasons, though these are not known in detail. Diabetes affects over 150 million people worldwide and this number is expected to double by 2025.
According to CDC, about 23.613 million people in the United States, or 8% of the population, have diabetes. The total prevalence of diabetes increased 13.5% from 2005-2007. It is thought that only 24% of diabetes is now undiagnosed, down from an estimated 30% in 2005 and from the previously estimated 50% in ca 1995.