One-Hour Plasma Glucose Better at Predicting Prediabetes Than Standard Tests: Study

Led by Dr. Muhammad Abdul-Ghani from the Diabetes Division at the University of Texas Health Science Center, San Antonio, the research analysed data from the long-running San Antonio Heart Study to explore how well 1-h PG concentrations during an oral glucose tolerance test (OGTT) can predict the onset of prediabetes among individuals with initially normal glucose tolerance (NGT).

The analysis included 1,557 adults who were free of type 2 diabetes at the beginning of the study. Each participant underwent an OGTT at baseline and a follow-up OGTT after an average of 7.5 years. Using American Diabetes Association criteria, the researchers evaluated how well the 1-h PG values could forecast the likelihood of progression to prediabetes.

The key findings of the study were as follows:

• At a 7.5-year follow-up, nearly 25% of individuals with normal glucose tolerance (NGT) at baseline progressed to prediabetes.
• 22.5% of participants with 1-hour plasma glucose (1-h PG) levels below 155 mg/dL progressed to prediabetes, compared to 42.5% of those with 1-h PG levels above 155 mg/dL.
• The 1-h PG level was the strongest predictor of future prediabetes risk among all glucose measures.
• A 1-h PG threshold of 120 mg/dL showed 61% sensitivity and 67% specificity in identifying individuals at high risk of developing prediabetes.
• Participants with 1-h PG levels between 120–155 mg/dL who developed prediabetes exhibited significant insulin resistance and metabolic abnormalities typical of insulin resistance syndrome.
• The authors suggested using the term "pre-prediabetes" to describe individuals with 1-h PG in the 120–155 mg/dL range, due to their higher risk of glucose deterioration.
• Elevated 1-h PG levels may serve as an early marker of metabolic dysregulation, appearing well before the onset of clinically defined prediabetes.
• Early identification of individuals with elevated 1-h PG levels could enable targeted interventions to prevent disease progression.

The authors concluded that a rise in 1-hour plasma glucose (1-h PG) levels occurs before the onset of prediabetes and can help identify individuals with 1-h PG between 120–155 mg/dL who are at a higher risk of developing prediabetes. They suggest referring to this group as "pre-prediabetes" to emphasize their elevated risk of worsening blood sugar levels.

The authors recommend incorporating 1-h PG measurements into clinical practice to improve risk assessment and guide targeted preventive strategies.

Reference:

Muhammad Abdul-Ghani, Mohamed Abu-Farha, Tamam Abdul-Ghani, Alberto Chavez-Velazquez, Auora Merovci, Ralph A. DeFronzo, Fahad Alajmi, Michael Stern, Fahd Al-Mulla; One-Hour Plasma Glucose Predicts the Progression From Normal Glucose Tolerance to Prediabetes. Diabetes Care 2025; dc242832. https://doi.org/10.2337/dc24-2832