The 1-hour Plasma Glucose Predicts the Progression from Normal Glucose Tolerance to Prediabetes

Objective: To examine the ability of the 1-hour plasma glucose (PG) concentration during the OGTT to predict the risk of progression to prediabetes in NGT individuals.

Research Design and Methods: A total of 1,557 subjects from the San Antonio Heart Study, who were free of type 2 diabetes at baseline; had baseline OGTT; and a repeat OGTT after 7.5 years of follow-up, were evaluated. The ability of 1-h PG concentration to predict the development of prediabetes -based upon the ADA criteria was evaluated.

Results: Approximately one quarter of NGT subjects (24.7%) progressed to prediabetes at 7.5 years (22.5% of NGT subjects with 1-h PG <155 mg/dl and 42.5% of NGT subjects with 1-h PG >155 mg/dl). The 1-hour PG was the strongest predictor of developing prediabetes and a 1-hour cut point of 120 mg/dl has 61% sensitivity and 67% specificity in identifying NGT individuals at high risk of developing prediabetes. Subjects with 1-h PG=120-155 mg/dl and who experienced a deterioration in glucose tolerance (progression to prediabetes) at follow-up were characterized by severe insulin resistance, and metabolic abnormalities characteristic of the insulin resistance syndrome. Therefore, we suggest the term “Pre-Prediabetes” for this group of NGT individuals to emphasize their high future risk of deteriorating glucose tolerance.

Conclusion: An increase in the 1-h PG concentration precedes the development of prediabetes, and identifies subjects with 1-h PG=120-155 mg/dl who are at increased risk of developing prediabetes. Therefore, we suggest the term Pre-Prediabetes for this group with an elevated risk of deteriorating glucose tolerance.