The evidence grading system for clinical practice recommendations (A through C, E) is defined at the end of the "Major Recommendations" field.
Classification and Diagnosis
Diagnosis of Diabetes
- The fasting plasma glucose (FPG) test is the preferred test to diagnose diabetes in children and nonpregnant adults. (E)
- Use of the glycated hemoglobin test (A1C) for the diagnosis of diabetes is not recommended at this time. (E)
| Criteria for the Diagnosis of Diabetes |
| 1. |
FPG >126 mg/dL (7.0 mmol/L). Fasting is defined as no caloric intake for at least 8 h*.
OR
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| 2. |
Symptoms of hyperglycemia and a casual plasma glucose >200 mg/dL (11.1 mmol/L). Casual is defined as any time of day without regard to time since last meal. The classic symptoms of diabetes include polyuria, polydipsia, and unexplained weight loss.
OR
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| 3. |
2-h plasma glucose >200 mg/dL (11.1 mmol/L) during an oral glucose tolerance test (OGTT). The test should be performed as described by the World Health Organization, using a glucose load containing the equivalent of 75-g anhydrous glucose dissolved in water.*
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*In the absence of unequivocal hyperglycemia, these criteria should be confirmed by repeat testing on a different day.
Although the OGTT is not recommended for routine clinical use, it may be useful for further evaluation of patients in whom diabetes is still strongly suspected but who have normal FPG or impaired fasting glucose (IFG).
Diagnosis of Pre-Diabetes
Hyperglycemia not sufficient to meet the diagnostic criteria for diabetes is categorized as either IFG or impaired glucose tolerance (IGT), depending on whether it is identified through the FPG or the OGTT:
- IFG = FPG 100 mg/dL (5.6 mmol/L) to 125 mg/dL (6.9 mmol/L)
- IGT = 2-h plasma glucose 140 mg/dL (7.8 mmol/L) to 199 mg/dL (11.0 mmol/L)
IFG and IGT have been officially termed "pre-diabetes."
Definitions:
American Diabetes Association's Evidence Grading System for Clinical Practice Recommendations
A
Clear evidence from well-conducted, generalizable, randomized controlled trials that are adequately powered, including:
- Evidence from a well-conducted multicenter trial
- Evidence from a meta-analysis that incorporated quality ratings in the analysis
- Compelling non-experimental evidence (i.e., "all or none" rule developed by the Center for Evidence Based Medicine at Oxford*)
Supportive evidence from well-conducted randomized, controlled trials that are adequately powered, including:
- Evidence from a well-conducted trial at one or more institutions
- Evidence from a meta-analysis that incorporated quality ratings in the analysis
*
Either all patients died before therapy and at least some survived with therapy, or some patients died without therapy and none died with therapy. Example: use of insulin in the treatment of diabetic ketoacidosis.
B
Supportive evidence from well-conducted cohort studies, including:
- Evidence from a well-conducted prospective cohort study or registry
- Evidence from a well-conducted meta-analysis of cohort studies
Supportive evidence from a well-conducted case-control study
C
Supportive evidence from poorly controlled or uncontrolled studies, including:
- Evidence from randomized clinical trials with one or more major or three or more minor methodological flaws that could invalidate the results
- Evidence from observational studies with high potential for bias (such as case series with comparison with historical controls)
- Evidence from case series or case reports
Conflicting evidence with the weight of evidence supporting the recommendation
E
Expert consensus or clinical experience
