Manual of Clinical Nutrition Management II- 21 Copyright © 2013 Compass Group, Inc.
DIAGNOSTIC CRITERIA FOR DIABETES MELLITUS^
The diagnostic criteria for diabetes are issued by the Expert Committee on the Diagnosis and Classification of
Diabetes Mellitus (1). In 2009, the Expert Committee on Diagnosis and Classification of Diabetes Mellitus
approved the use of the A1C test for diagnosing diabetes mellitus after extensive review of the literature and
improved standardization of the assay (1). This system of classification of diabetes is based on the cause of
the disease, as opposed to the therapy used to treat the hyperglycemia.
Diagnosis of Diabetes
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus advocates use of the following
laboratory criteria for nonpregnant adults (1):
- Symptoms of diabetes plus casual plasma glucose concentration greater than or equal to 200 mg/dL
(11.1 mmol/L). Casual is defined as any time of the day without regard to the time since the last meal.
The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss. - Fasting plasma glucose (FPG) concentration greater than or equal to 126 mg/dL (7.0 mmol/L). Fasting
is defined as no energy intake for at least 8 hours. - Plasma glucose concentration 2 hours after glucose ingestion greater than or equal to 200 mg/dL during
an oral glucose tolerance test (OGTT). The test should be performed, as described by the World Health
Organization (WHO), using a glucose load containing the equivalent of 75 g of anhydrous glucose
dissolved in water. - A1C test greater than or equal to 6.5%. Test should be performed in a laboratory using a method that is
National Glycohemoglobin Standardization Program (NGSP) certified and standardized to the Diabetes
Control and Complications Trial (DCCT) assay.
In the absence of unequivocal hyperglycemia with acute metabolic decompensation, these criteria should be
confirmed by repeated testing on a different day. The OGTT is not recommended for routine clinical use (1).
Impaired Fasting Glucose (IFG) and Impaired Glucose Tolerance (IGT)
The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus endorses the following criteria
for the diagnosis of diabetes mellitus and gestational diabetes (1). The Expert Committee recognizes an
intermediate group of patients whose glucose levels, although do not meet the criteria for diabetes, are too
high to be considered normal. This group is now referred to as “pre-diabetes” indicating the relatively high
risk for development of diabetes in these patients (1):
(^) “Normal” (^) “Pre-diabetes” (^) “Diabetes”
Fasting plasma glucose^ <100 mg/dL^ Impaired Fasting Glucose (IFG)
100 and <125 mg/dL (IFG)^
126 mg/dL
Glucose tolerance, at 2 hours
after glucose load (during
OGTT)^
<140 mg/dL^
Impaired Glucose Tolerance (IGT)
140 to 199 mg/dL (IGT)^ >200 mg/dL^
A1C Test 4.5 to 5.5 % 5.7 % to 6.4% > 6.5 %
Based on the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study, the International Association
of Diabetes and Pregnancy Study Group (IADPSG) has modified diagnostic criteria for gestational diabetes (1-
3). These new criteria will significantly increase the prevalence of GDM, primarily because only one abnormal
value, not two is sufficient to make the diagnosis (1).
Screening and Diagnosis of Gestational Diabetes Mellitus (GDM) (1-3)
Plasma Glucose 75 - g Diagnostic Test (mg/dL)
Fasting > 92
1 h postprandial > 180
2 h postprandial - > 153
Note: High risk women (e.g., marked obesity, history of GDM, glycosuria, or strong family history of diabetes) should undergo glucose
testing during the initial prenatal care visit for a diagnosis of overt diabetes. All women not known to have diabetes should undergo a
75 - g OGTT at 24 to 28 weeks of gestation.
The 75-g oral-glucose tolerance test should be performed on pregnant women not known to have diabetes at 24 to 28 weeks of
gestation. The diagnosis of GDM requires any one of the three plasma glucose values obtained during the test to meet or exceed the
values shown above. The test should be done in the morning after an overnight fast of between 8 hours.