According to the 2020 Prevention Diabetes Surveillance System and the Centers for Disease Control estimates, nearly 88 million adults in the US 18 years or older had prediabetes in 2018.1 As prediabetes is a strong risk factor for developing type 2 diabetes (T2DM) and other health conditions, it is important to understand how to identify and prevent prediabetes.


What Is Prediabetes?

The term “prediabetes” is used when an individual does not meet the diagnostic criteria for diabetes but has glucose levels too high to be considered normal.2

Individuals who meet any one of the following clinical criteria are defined as having prediabetes, according to the American Diabetes Association (ADA):

  • Impaired Fasting Glucose (IFG)*
    • Fasting plasma glucose (FPG) levels: 100-125 mg/dL, or
  • Impaired Glucose Tolerance (IGT)
    • 2-hour plasma glucose during 75 g oral glucose tolerance test: 140-199 mg/dL, or
  • Elevated Glycosylated Hemoglobin (A1C)
    • A1C levels: 5.7-6.4%

*IFG cutoff is set at 110 mg/dL by the World Health Organization along with other diabetic organizations.


Why Is It Important to Know If You Have Prediabetes?

Prediabetes is not a clinical diagnostic entity but rather a risk factor for T2DM and cardiovascular disease (CVD).2 Risks assessed by the three different tests (ie, IFG, IGT, and A1C) are continuous, meaning that the risks become disproportionately greater at the higher end of the ranges.

Several prospective studies have found a strong and continuous association between A1C levels and subsequent diabetes.3–7 A review of 16 cohort studies found that the 5-year risk of developing T2DM increased with A1C levels; individuals with A1C range of 5.5-6.0% had a 9-25% risk and those with A1C range of 6.0-6.5% had a 25-50% risk, 20 times higher than individuals with A1C of 5.0%.3

Additionally, prediabetes is also associated with comorbidities that usually develop as a complication of diabetes, especially CVD.8–10 Both diabetes and prediabetes share similar pathophysiology involving hyperglycemia and insulin resistance that predispose individuals to macrovascular complications.11 A meta-analysis of 53 prospective studies concluded that prediabetes was associated with a significantly increased risk of CVD, coronary heart disease, stroke, and all-cause mortality.12 Other surveys and studies suggest that individuals with prediabetes are at an increased risk of developing CVD, peripheral vascular disease, ischemic heart disease, autonomic neuropathy, and chronic kidney disease, along with other chronic conditions.8,9

However, despite the long-term health risks associated with prediabetes, on average, individuals remain in their prediabetic state for 10 years before developing overt diabetes, providing a wide window of opportunity for intervention.13,14 Since the risk of developing T2DM and CVD rises disproportionately with increasing glucose and A1C levels,2,3 the ADA recommends those with IFG and/or IGT and/or elevated A1C to be informed of their risks and to begin aggressive interventions.2 Additionally, annual screening for individuals with prediabetes and/or other risk factors can allow for earlier diagnosis and treatment to improve long-term health outcomes.2


1. National Diabetes Statistics Report 2020. Estimates of diabetes and its burden in the United States. Published online 2020:32.
2. American Diabetes Association. 2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes-2021. Diabetes Care. 2021;44(Suppl 1):S15-S33. doi:10.2337/dc21-S002
3. Zhang X, Gregg EW, Williamson DF, et al. A1C level and future risk of diabetes: A systematic review. Diabetes Care. 2010;33(7):1665-1673. doi:10.2337/dc09-1939
4. Selvin E, Steffes MW, Zhu H, et al. Glycated hemoglobin, diabetes, and cardiovascular risk in nondiabetic adults. N Engl J Med. 2010;362(9):800-811. doi:10.1056/NEJMoa0908359
5. Ackermann RT, Cheng YJ, Williamson DF, Gregg EW. Identifying adults at high risk for diabetes and cardiovascular disease using hemoglobin A1c: National Health and Nutrition Examination Survey 2005–2006. Am J Prev Med. 2011;40(1):11-17. doi:10.1016/j.amepre.2010.09.022
6. Diabetes Prevention Program Research Group. HbA1c as a predictor of diabetes and as an outcome in the Diabetes Prevention Program: A randomized clinical trial. Diabetes Care. 2014;38(1):51-58. doi:10.2337/dc14-0886
7. Glauber H, Vollmer WM, Nichols GA. A simple model for predicting two-year risk of diabetes development in individuals with prediabetes. Perm J. 2018;22:17-050. doi:10.7812/TPP/17-050
8. Iranfar N. When should “pre” carry as much weight in the diabetes comorbidity debate? Insights from a population-based survey. Prev Chronic Dis. 2018;15. doi:10.5888/pcd15.170158
9. Farrell C, Moran J. Comparison of comorbidities in patients with pre-diabetes to those with diabetes mellitus type 2. Ir Med J. 2014;107(3):72-74.
10. CDC. The surprising truth about prediabetes. Centers for Disease Control and Prevention. Published July 7, 2022. Accessed July 15, 2022.
11. Huang D, Refaat M, Mohammedi K, Jayyousi A, Al Suwaidi J, Abi Khalil C. Macrovascular complications in patients with diabetes and prediabetes. Biomed Res Int. 2017;2017:e7839101. doi:10.1155/2017/7839101
12. Huang Y, Cai X, Mai W, Li M, Hu Y. Association between prediabetes and risk of cardiovascular disease and all cause mortality: systematic review and meta-analysis. BMJ. 2016;355:i5953. doi:10.1136/bmj.i5953
13. Khetan AK, Rajagopalan S. Prediabetes. Can J Cardiol. 2018;34(5):615-623. doi:10.1016/j.cjca.2017.12.030
14. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol. 2015;3(11):866-875. doi:10.1016/S2213-8587(15)00291-0



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