|New recommendations about the diagnosis and classification of diabetes mellitus have been published in the July 1997 issue of Diabetes Care, marking the first changes since 1979.
These recommendations were made by an expert committee and have been accepted and are supported by the American Diabetes Association, the National Institute of Diabetes and Digestive and Kidney Diseases, and the Centers for Disease Control and Prevention, Division of Diabetes Translation.
The following is a summary of major recommendations.
- Eliminate "insulin-dependent diabetes mellitus" (IDDM) and "noninsulin-dependent diabetes mellitus" (NIDDM).
- Keep the terms "type 1" and "type 2," but use Arabic rather than Roman numerals.
- Type 1 diabetes is characterized by beta cell destruction, usually leading to absolute insulin deficiency. It has two forms: Immune-Mediated Diabetes Mellitus and Idiopathic Diabetes Mellitus. Immune-Mediated
- Diabetes Mellitus results from a cellular mediated autoimmune destruction of the beta cells of the pancreas. Idiopathic type 1 refers to forms of the disease that have no known etiologies.
- Type 2 diabetes is defined as a term for individuals who have insulin resistance and usually have relative (rather than absolute) insulin deficiency. People with type 2 can range from predominantly insulin resistant with relative insulin deficiency to predominantly deficient in insulin secretion with insulin resistance.
- The stage called "impaired glucose tolerance" (based on the oral glucose tolerance test) is retained, and an analogous stage called "impaired fasting glucose" (derived from the fasting plasma glucose test) has been defined. Both terms refer to a metabolic stage intermediate between normal glucose homeostasis and diabetes, and although not clinical entities in their own right (in the absence of pregnancy), they are risk factors for future diabetes and cardiovascular disease.
- Gestational Diabetes Mellitus (GDM) is retained; however, selective screening, rather than universal screening, for glucose intolerance in pregnancy is now recommended. Low-risk women are: Less than 25 years of age, normal body weight, have no family history of diabetes mellitus and are NOT a member of an ethnic/racial group with a high prevalence of diabetes (Hispanic, African American, Native American, Asian). No change is recommended to the current diagnostic criteria for GDM.
- A fasting plasma glucose of 110 mg/dl has been chosen as the upper limit of "normal."
Diagnostic criteria have been modified from those previously recommended (see chart below). Three ways to diagnose diabetes are possible, but one?the fasting plasma glucose (FPG) test?is preferred.
An FPG value 2126 mg/dl (confirmed by repeat testing) is diagnostic for diabetes. This recommendation is based on new research showing a sharp rise in adverse outcomes (i.e., microvascular complications) at or near this blood glucose level and an increased risk for macrovascular disease.
The revised criteria are for diagnosis and are not treatment criteria or goals of therapy.
Criteria for Testing in Asymptomatic, Undiagnosed Individuals
Type 1 Diabetes: Testing presumably healthy individuals for the presence of any immune markers, outside of a clinical trials setting, is not recommended.
Type 2 Diabetes: In asymptomatic, undiagnosed individuals, testing for diabetes should be considered in all individuals at age 45 years and above and, if normal, it should be repeated at three year intervals. Testing should be considered at a younger age, or be carried out more frequently, in individuals who:
The FPG is the preferred diagnostic test because of its ease of administration, convenience, acceptability to patients, and lower cost.
- are obese (2120% desirable body weight or a body mass index (BMI) 227 kg/m2)
- have a first degree relative with diabetes
- are members of a high-risk ethnic population (African American, Hispanic, Native American, Asian)
- delivered a baby weighing > 9 lb. or was diagnosed with GDM
- are hypertensive (2140/90)
- have an HDL-C level <35mg/dl and/or a triglyceride level 2250 mg/dl
- on previous testing, had IGT or IFG.
Glucose (FPG) Test
||FPG 2126 mg/dl
(7.0 mmol/l) (2)
|Casual plasma glucose
>=220 mg/dl (11.1 mmol/l)
plus symptoms (3)
|Two-hour plasma glucose (2hPG) >=220 mg/dl (4)
|Impaired Glucose Homeostasis
||Impaired Fasting Glucose (IFG) =
FPG >=110 and
Tolerance (IGT) = 2hPG
>=140 and <200 mg/dl
||FPG <110 mg/dl
||2hPG <140 mg/dl
(1) The FPG is the preferred test for diagnosis, but any one of the three listed is acceptable. In the absence of unequivocal hyperglycemia with acute metabolic decompensation, one of these three tests should be used on a different day to confirm diagnosis.
(2) Fasting is defined as no caloric intake for at least 8 hours.
(3) Casual = any time of day without regard to time since last meal; symptoms are the classic ones of polyuria, polydipsia, and unexplained weight loss.
(4) OGTT should be performed using a glucose load containing the equivalent of 75g anhydrous glucose dissolved in water. The OGTT is not recommended for routine clinical use.