What are the diagnostic criteria for diagnosis?

From the Guidelines

Diabetes can be diagnosed based on A1C or plasma glucose criteria, including fasting plasma glucose, 2-h plasma glucose during a 75-g oral glucose tolerance test, or random glucose accompanied by classic hyperglycemic symptoms or hyperglycemic crises, as stated in the most recent guidelines 1. The diagnostic criteria for diabetes have been well-established and are based on a combination of laboratory test results and clinical presentation.

• The criteria include:
  • A1C criteria
  • Plasma glucose criteria, such as fasting plasma glucose (FPG) or 2-h plasma glucose (2-h PG) during a 75-g oral glucose tolerance test (OGTT)
  • Random glucose accompanied by classic hyperglycemic symptoms, such as polyuria, polydipsia, and unexplained weight loss, or hyperglycemic crises, including diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar state (HHS) 1. It is essential to note that these criteria are equally appropriate for diagnostic testing, but the detection rates of different screening tests may vary in both populations and individuals 1.
• In certain conditions, such as sickle cell disease, pregnancy, hemodialysis, recent blood loss or transfusion, or erythropoietin therapy, only plasma blood glucose criteria should be used to diagnose diabetes 1. The most recent guidelines, published in 2025, provide the most up-to-date information on the diagnostic criteria for diabetes, and healthcare professionals should use these guidelines in conjunction with clinical judgment and individual patient factors to make an accurate diagnosis and develop an appropriate treatment plan 1.

From the Research

Diagnostic Criteria

The diagnostic criteria for various medical conditions have been developed and revised over time to improve accuracy and effectiveness in diagnosis and treatment.

• The World Health Organisation (WHO) and the American Diabetes Association (ADA) have published revised criteria for the classification and diagnosis of diabetes 2.
• Clinicians require accurate and reliable diagnostic criteria for conditions they evaluate, which is the basis for rational and effective treatment and estimation of a meaningful prognosis 3.
• Diagnostic criteria should be based on evidence from rigorously conducted controlled studies, and formal group consensus methods can be used to organize subjective judgments and synthesize them with available evidence 4.

Development of Diagnostic Criteria

The development of diagnostic criteria involves various approaches, including:

• The Delphi method, Nominal Group Technique, RAND/UCLA Appropriateness Method, and National Institutes of Health consensus development conference 4.
• Multidimensional frameworks, such as the ACTTION-American Pain Society Pain Taxonomy (AAPT), which provides a systematic approach to developing diagnostic criteria for chronic pain conditions 5.
• Consensus recommendations, such as the MENACTRIMS guidelines, which provide practical recommendations and algorithms for the diagnosis and treatment of multiple sclerosis based on current scientific evidence and clinical experience 6.

Importance of Diagnostic Criteria

Accurate and reliable diagnostic criteria are essential for:

• Improving health outcomes for patients 4.
• Reducing variations in care 3.
• Advancing the scientific understanding of medical conditions and their treatment 5.
• Guiding clinical decision-making and improving the quality of clinical research 5.