The Oral Glucose Tolerance Test: 100 Years Later

Area of Science:

• Endocrinology
• Metabolic Disorders
• Clinical Diagnostics

Background:

• The oral glucose tolerance test (OGTT) has been a primary tool for diagnosing prediabetes and type 2 diabetes (T2DM) for over a century.
• Current diagnostic criteria using fasting plasma glucose (FPG), 2-hour post-load glucose (2-h PG), and HbA1c have faced controversies regarding international cut points.
• Despite debates, the 2-h PG remains globally accepted for defining dysglycemic states within the OGTT framework.

Purpose of the Study:

• To review the historical context and recent advancements in OGTT applications.
• To evaluate the limitations of FPG, 2-h PG, and HbA1c in diagnosing diabetes.
• To examine the association between 30-minute and 1-hour plasma glucose (1-h PG) levels and the incidence of diabetes and its complications.

Main Methods:

• Review of historical data and scientific literature on OGTT.
• Analysis of recent applications, including the glucose challenge test and mathematical modeling of glucose curves.
• Examination of evidence linking 1-h PG levels to diabetes incidence and complications.

Main Results:

• The 1-h PG measurement during OGTT is associated with a higher likelihood of identifying individuals at risk for diabetes.
• Early detection via 1-h PG may capture individuals with more preserved pancreatic beta-cell function.
• The 1-h PG offers a potential alternative to the conventional 2-h OGTT, enhancing clinical practicality.

Conclusions:

• Considerable evidence supports incorporating 1-h PG measurements into current screening and diagnostic recommendations.
• Utilizing 1-h PG can improve the early identification of high-risk individuals for diabetes.
• The 1-h PG may offer a more efficient and acceptable clinical approach compared to the traditional 2-h OGTT.