The evidence grading system (A-C, E) is defined at the end of the "Major Recommendations" field.
Prevention/Delay of Type 2 Diabetes
- Patients with impaired glucose tolerance (IGT) (A) or impaired fasting glucose (IFG) (E) should be given counseling on weight loss of 5% to 10% of body weight, as well as on increasing physical activity to at least 150 min/week of moderate activity such as walking.
- Follow-up counseling appears to be important for success. (B)
- Based on potential cost savings of diabetes prevention, such counseling should be covered by third-party payors. (E)
- In addition to lifestyle counseling, metformin may be considered in those who are at very high risk (combined IFG and IGT plus other risk factors) and who are obese and under 60 years of age. (E)
- Monitoring for the development of diabetes in those with pre-diabetes should be performed every year. (E)
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:
- Evidence from a well-conducted prospective cohort study or registry
- Evidence from a well-conducted prospective cohort study
- 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