Using HbA1c to define prediabetes was more specific and led to modest improvements in risk discrimination for clinical complications in a prospective cohort analysis involving nearly 11,000 individuals. Additionally, the ADA fasting glucose cutoff provided the most sensitive definition of prediabetes.

Participants were from the ARIC study and did not have diabetes at baseline. Investigators measured fasting glucose, HbA1c, and 2 h glucose levels. They compared prediabetes definitions based on ADA and WHO cutoffs for fasting glucose; ADA and IEC cutoffs for HbA1c; and ADA and WHO cutoff for 2 h glucose. Among the results:

• Defining prediabetes using ADA fasting glucose cutoff (38% prevalence) was the most sensitive.
• Using the ADA HbA1c (19% prevalence), IEC HbA1c (9% prevalence), and WHO fasting glucose (11% prevalence) cutoffs provided more specificity.
• HbA1c-based definitions predicted risk better for kidney, CV, and peripheral arterial diseases, as well as for all-cause mortality, compared with fasting glucose-based definitions.