Diagnostic Criteria for Diabetes Mellitus

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). 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.

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 (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 <126 mg/dL (IFG)	>126 mg/dL
Glucose tolerance, at 2 hours after glucose load (during OGTT)	<140 mg/dL	Impaired Glucose Tolerance (IGT) >140 and <200 mg/dL (IGT)	>200 mg/dL

Screening and Diagnosis Scheme for Gestational Diabetes Mellitus (GDM) (2,3)

Plasma Glucose	50-g Screening Test (mg/dL)	*100-g Diagnostic Test (mg/dL)**
Fasting	--	95
1 h postprandial	130-140	180
2 h postprandial	--	155
3 h postprandial	--	140

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, if found to not have GDM should be retested at 24 and 28 weeks gestation. Screening should be performed between the 24th and 28th weeks of gestation in women with average risk meeting one or more of the following criteria: >25 years of age; a body mass index (BMI)>25 kg/m2); family history of diabetes in first-degree relatives; history of abnormal glucose tolerance, and/or member of an ethic/racial group with a high prevalence of diabetes (eg, Hispanic-American, Native American, Asian-American, African-American, or Pacific Islander).

*The 100-g diagnostic test is performed on patients who have a positive screening test. The diagnosis of GDM requires any two of the four 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 and 14 hours and after at least 3 days of unrestricted diet (> 150 g Carbohydrate per day) and unlimited physical activity.

References

American Diabetes Association. Diagnosis and Classification of Diabetes Mellitus: position statement. Diabetes Care. 2008;31 (suppl 1):55S-60S.
American Diabetes Association. Gestational diabetes mellitus: position statement. Diabetes Care. 2004;27(suppl 1):88S-90S.
ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists. Number 30, September 2001 (replaces Technical Bulletin Number 200, December 1994). Gestational Diabetes. Obstet Gynecol. 2001; 98:525-538.

Bibliography

The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus: Report of the Expert Committee on Diagnosis and Classification of Diabetes Mellitus. Diabetes Care. 1997;20: 1183-1197.
American Diabetes Association. Implications of the diabetes control and complications trial: position statement. Diabetes Care. 2002;25 (suppl 25S-27S.
American Diabetes Association. Implications of the United Kingdom Prospective Diabetes Study. Diabetes Care. 2002;25: (suppl 1): 28S-32S.

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