Paul S. Mueller, MD, MPH, FACP reviewing Huang Y et al. BMJ 2016 Nov 23

But the extent of excess risk depends on the threshold used to define prediabetes.

The extent to which prediabetes predisposes people to adverse cardiovascular (CV) outcomes is unclear. A reason for inconsistent findings might be the varied definitions for prediabetes:

• The American Diabetes Association (ADA) defines prediabetes as impaired fasting glucose (100–125 mg/dL), impaired glucose tolerance (2-hour glucose level of 140–199 mg/dL during an oral glucose tolerance test), or glycosylated hemoglobin (HbA1c) level of 5.7% to 6.4%.
• Compared with the ADA definitions, the World Health Organization and the U.K. National Institute for Health and Care Excellence (UK NICE) use a higher threshold for impaired fasting glucose (110 mg/dL).
• Compared with the ADA definitions, UK NICE uses higher values for HbA1c (6.0%–6.4%).

In this meta-analysis of 53 prospective cohort studies (mean follow-up, 9.5 years), researchers determined the associations between various definitions of prediabetes and risk for adverse CV outcomes and all-cause death.

Compared with normoglycemia, the 100 mg/dL fasting threshold, the 110 mg/dL fasting threshold, and the impaired glucose tolerance definitions of prediabetes were associated with 13%, 26%, and 30% higher risks for composite CV disease, respectively. Similar results were obtained for coronary heart disease, stroke, and death. The 5.7% and 6.0% HbA1c thresholds were associated with a 21% and 25% higher risk, respectively, for composite CV disease and a 15% and 28% higher risk for coronary heart disease.

CITATION(S):

Huang Y et al. Association between prediabetes and risk of cardiovascular disease and all cause mortality: Systematic review and meta-analysis. BMJ 2016 Nov 23; 355:i5953. 

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