From the Guidelines
Type 2 diabetes is diagnosed when a patient meets one or more of the following criteria: a fasting plasma glucose level of 126 mg/dL (7.0 mmol/L) or higher, a 2-hour plasma glucose level of 200 mg/dL (11.1 mmol/L) or higher during an oral glucose tolerance test, a random plasma glucose level of 200 mg/dL or higher in a patient with classic symptoms of hyperglycemia, or a hemoglobin A1C level of 6.5% or higher 1. The diagnosis should be confirmed by repeating the test on another day unless symptoms are clear and glucose levels are markedly elevated.
Key Diagnostic Criteria
- Fasting plasma glucose level of 126 mg/dL (7.0 mmol/L) or higher
- 2-hour plasma glucose level of 200 mg/dL (11.1 mmol/L) or higher during an oral glucose tolerance test
- Random plasma glucose level of 200 mg/dL or higher in a patient with classic symptoms of hyperglycemia
- Hemoglobin A1C level of 6.5% or higher Risk factors that warrant screening include age over 45, obesity, family history of diabetes, physical inactivity, certain ethnicities, history of gestational diabetes, and conditions associated with insulin resistance like polycystic ovary syndrome 1.
Risk Factors for Type 2 Diabetes
- Age over 45
- Obesity
- Family history of diabetes
- Physical inactivity
- Certain ethnicities
- History of gestational diabetes
- Conditions associated with insulin resistance like polycystic ovary syndrome Early diagnosis is crucial because type 2 diabetes often develops gradually, and many patients remain asymptomatic for years while high blood glucose levels damage their bodies 1.
Importance of Early Diagnosis
- Allows for earlier intervention with lifestyle modifications and medications if needed
- Potentially prevents or delays complications such as cardiovascular disease, neuropathy, nephropathy, and retinopathy Timely diagnosis and intervention can significantly improve morbidity, mortality, and quality of life for patients with type 2 diabetes 1.
From the Research
Diagnosis of Type 2 Diabetes
The diagnosis of type 2 diabetes can be made using various tests, including:
- Fasting plasma glucose
- Hemoglobin A1c (HbA1c)
- Oral glucose tolerance test (OGTT)
- Random plasma glucose 2
Diagnostic Criteria
The diagnostic criteria for type 2 diabetes include:
- Fasting plasma glucose ≥ 126 mg/dl (7.0 mmol/l) 3
- Casual plasma glucose ≥ 200 mg/dl (11.1 mmol/l) in the presence of symptoms 3
- 2-h plasma glucose during the 75-g OGTT ≥ 200 mg/dl (11.1 mmol/l) 3
- HbA1c ≥ 6.5% 4, 3
Limitations of HbA1c
HbA1c has some limitations as a diagnostic tool, including:
- It may not be accurate in certain individuals, such as those with hemoglobinopathies or chronic kidney disease 4
- It may not detect all cases of diabetes, particularly those with impaired glucose tolerance 5
- It may be affected by factors such as age, sex, and body mass index (BMI) 5
Combination of Tests
Using a combination of tests, such as HbA1c and fasting plasma glucose, may be more effective in diagnosing type 2 diabetes than relying on a single test 2, 4
- If an HbA1c test result is discordant with the clinical picture or equivocal, plasma glucose testing should be performed 4
- The diagnostic agreement in the clinical setting revealed that the current HbA1c ≥ 6.5% is less likely to detect diabetes than those defined by fasting plasma glucose and 2-h plasma glucose 5