IV. PREVENTION/DELAY OF TYPE 2 DIABETES

Recommendations

• Patients with IGT or IFG should be referred to an effective ongoing support program for weight loss of 5–10% of body weight and for increasing physical activity to at least 150 min per week of moderate activity such as walking.
• Follow-up counseling appears to be important for success.
• Based on potential cost savings of diabetes prevention, such counseling should be covered by third-party payers.
• In addition to lifestyle counseling, metformin may be considered in those who are at very high risk for developing diabetes (combined IFG and IGT plus other risk factors such as A1C >6%, hypertension, low HDL cholesterol, elevated triglycerides, or family history of diabetes in a first-degree relative) and who are obese and under 60 years of age.
• • Monitoring for the development of diabetes in those with pre-diabetes should be performed every year.

Randomized controlled trials have shown that individuals at high risk for developing diabetes (those with IFG, IGT, or both) can be given interventions that significantly decrease the rate of onset of diabetes. These interventions include intensive lifestyle modification programs that have been shown to be very effective (≥58% reduction after 3 years) and use of the pharmacologic agents metformin, acarbose, orlistat, and thiazolidinediones (TZDs), each of which has been shown to decrease incident diabetes to various degrees.

Two studies of lifestyle intervention have shown persistent reduction in the rate of conversion to Type 2 diabetes with 3 to 14 years of postintervention follow-up.

Based on the results of clinical trials and the known risks of progression of pre-diabetes to diabetes, an ADA Consensus Development Panel concluded that persons with pre-diabetes (IGT and/or IFG) should be counseled on lifestyle changes with goals similar to those of the Diabetes Prevention Program (DPP) (5–10% weight loss and moderate physical activity of ∼30 min per day). Regarding the more difficult issue of drug therapy for diabetes prevention, the consensus panel felt that metformin should be the only drug considered for use in diabetes prevention. For other drugs, the issues of cost, side effects, and lack of persistence of effect in some studies led the panel to not recommend their use for diabetes prevention. Metformin use was recommended only for very-high-risk individuals (those with combined IGT and IFG who are obese and under 60 years of age with at least one other risk factor for diabetes). In addition, the panel highlighted the evidence that in the DPP, metformin was most effective compared to lifestyle in those with BMI of at least 35 kg/m2 and those under age 60 years.