Overview: Glucose 2H Post 75g TestIntroduction: The Glucose 2H Post 75g Test measures glucose 2 hours after a 75g load to diagnose diabetes, causing thirst or frequent urination. Following 2023 ADA guidelines, it uses spectrophotometry for high sensitivity, aiding in metabolic screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in biochemistry for patients with suspected diabetes. It is a standard endpoint in the oral glucose tolerance test (OGTT) for non-pregnant individuals.
Other Names: Glucose 2H 75g Assay, OGTT 2H Test.
FDA Status: Laboratory-developed test (LDT), meeting biochemistry standards for diagnostic accuracy.
Historical Milestone: The 75g OGTT was standardized in the 1980s for diabetes diagnosis. Spectrophotometry advancements in the 1990s improved glucose measurement accuracy.
Purpose: Diagnoses diabetes, guides treatment, and monitors glucose levels in patients with thirst, frequent urination, or fatigue.
Test Parameters: 1. Glucose (2.0 H Post 75g)
Pretest Condition: Fasting for 10-12 hours required. Collect plasma or serum 2 hours after 75g glucose load. Report symptoms like thirst, frequent urination, or fatigue, and list medications.
Specimen: 2-4 mL plasma (NaF) or 2-5 mL serum (SST). Centrifuge within 1 hour. Transport in a biohazard bag within 24 hours.
Sample Stability at Room Temperature: 24 hours
Sample Stability at Refrigeration: 48 hours
Sample Stability at Frozen: Not frozen
Medical History: Document thirst, frequent urination, fatigue, or history of diabetes. Include current medications, especially antidiabetics, and family history.
Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for diabetes treatment or lifestyle changes.
Procedural Considerations: Uses spectrophotometry to measure glucose levels 2 hours post-75g load. Results are available in 1-2 days, enabling rapid clinical decisions. Performed in laboratories, often the primary endpoint in OGTT.
Factors Affecting Result Accuracy: Non-fasting, improper timing, hemolysis, or medications (e.g., corticosteroids) can affect results. Stress or illness may alter glucose levels.
Clinical Significance: Elevated glucose levels suggest diabetes, prompting treatment (e.g., insulin, lifestyle changes). Normal levels may require further testing to confirm.
Specialist Consultation: Consult an endocrinologist for result interpretation and diabetes management planning.
Additional Supporting Tests: 1-hour OGTT, HbA1c, fasting glucose, or C-peptide to confirm diabetes diagnosis.
Test Limitations: Single time-point results may miss dynamic glucose changes. Results require clinical correlation and multi-point testing for accuracy.
References: ADA Diabetes Guidelines, 2023; Diabetes Care, Nathan DM, 2022.
