The criteria for the diagnosis of diabetes mellitus and impaired glucose tolerance have been modified over time. The most recent recommendation includes use of glycosylated hemoglobin A1c.
(1) casual (random) glucose concentration: performed any time during the day without regard to time since the last meal
(2) fasting plasma glucose concentration: no caloric intake for at least 8 hours
(3) oral glucose tolerance test: performed using the World Health Organization (WHO) guidelines using a solution containing the equivalent of 75 grams (anhydrous) glucose dissolved in water. This is not recommended for routine clinical use.
Criteria for Diabetes Mellitus
Diabetes Mellitus is considered present if
(1) one or more of the following criteria is present AND
(2) one of the following:
(2a) unequivocal hyperglycemia and acute metabolic decompensation is present (criterion 1)
(2b) presence of one or more criteria on repeat testing by the same method on a subsequent day
Criterion 1 – both of the following:
(1) symptoms of diabetes (polyuria, polydipsia, unexplained weight loss), AND
(2) casual plasma glucose concentration >= 200 mg/dL (>= 11.1 mmol/L)
Criterion 2: fasting plasma glucose concentration >= 126 mg/dL (>= 7.0 mmol/L)
Criterion 3: A 2 hour plasma glucose >= 200 mg/dL during an oral glucose tolerance test performed as described by the WHO
Criterion 4: A glycosylated hemoglobin A1c >= 6.5% on a laboratory analyzer (not point of care device) in a patient without hemoglobinopathy, hemolytic anemia or recent blood transfusion.
Criteria for Impaired Glucose Homeostasis
Impaired fasting glucose (IFT): fasting plasma glucose concentration >= 100 mg/dL and < 126 mg/dL
Impaired glucose tolerance (IGT): A 2 hour plasma glucose >= 140 mg/dL and < 200 mg/dL during an oral glucose tolerance test performed as described by the WHO.
Since the oral glucose tolerance test cutoff of 140 mg/dL at 2 hours after glucose load will identify more people as having impaired glucose homeostasis than the fasting glucose cutoff of 100 mg/dL, the test used should always be reported.
A glycosylated hemoglobin A1c from 6.0 to 6.4%.
"Normal" Glucose Homeostasis
Some patients in the continuum of diabetes may show early pathologic changes while still in the "normal" range.
Normal fasting glucose: fasting plasma glucose concentration < 100 mg/dL
Normal glucose tolerance: A 2 hour plasma glucose < 140 mg/dL during an oral glucose tolerance test performed as described by the WHO
A glycosylated hemoglobin A1c from < 6.0%.
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Purpose: To evaluate a patient for diabetes mellitus using the 2009 recommendations.
Specialty: Endocrinology, Clinical Laboratory
Objective: criteria for diagnosis