Added citation to a journal article published in Diabetes Care which analyzes data from the 2006 NHANES survey give an accurate idea of what the actual incidence of diabetes and prediabetes are in the American population.
Full Accounting of Diabetes and Pre-Diabetes in the U.S. Population in 1988–1994 and 2005–2006. Catherine C. Cowie et al. Diabetes Care 32:287-294, 2009.
This study reports,
In 2005–2006, the crude prevalence of total diabetes in people aged ≥20 years was 12.9%, of which ~40% was undiagnosed. In people aged ≥20 years, the crude prevalence of impaired fasting glucose was 25.7% and of impaired glucose tolerance was 13.8%, with almost 30% having either. Over 40% of individuals had diabetes or pre-diabetes. Almost one-third of the elderly had diabetes, and three-quarters had [either] diabetes or pre-diabetes.Though the incidence of diagnosed diabetes had increased, the increase was slightly over 2% which may be due to better diagnosis, not more diabetes.
I take the high incidence of "prediabetes" compared to the modest prevalence of full fledged diabetes--much of it occurring in the elderly--as an indication that most people with "prediabetes" are not likely to become fully diabetic, though they may experience blood sugar related hunger and weight gain.
Only those with the underlying genetic flaws that prevent beta cell mass to expand or limit insulin secretion are likely to go on to become fully diabetic.