The High Risk Approach
IDF proposes a simple three step plan for the prevention of type 2 diabetes in those at increased risk:
Step 1: Identification of those who may be at higher risk
The new IDF consensus recommends that all individuals at high risk of developing type 2 diabetes be identified through opportunistic screening by doctors, nurses, pharmacists and through self-screening. In any population, individuals at high risk can be easily identified through a simple, practical and non-invasive questionnaire, such as the Finnish Type 2 Diabetes Risk Assessment Form, which focuses on risk factors such as age, waist circumference, family history, cardiovascular history, gestational history and drug history.
Step 2: Measurement of risk
Individuals at high risk should then have their plasma glucose levels measured by a health professional. This will not only detect cases of IFG (Impaired Fasting Glucose) or IGT (Impaired Glucose Tolerance), but also cases of undiagnosed diabetes. The presence of IGT and IFG give a considerably increased risk of developing type 2 diabetes. Interventions targeted at such individuals therefore provide an opportunity to delay or prevent the onset of type 2 diabetes.
Other diabetic risk factors that should also be assessed at this stage include the presence of increased waist circumference; high blood pressure; family history of diabetes; raised triglycerides; or a pre-existing cardiovascular disease. The presence of any of these factors will increase a person’s risk of developing diabetes.
Country/ethnic specific values for waist circumference
These are pragmatic cut points and better data are required to link them to risk. Ethnicity should be the basis for classification, not the country of residence.
*In the USA the ATP III values (102 cm male; 88 cm female) are likely to continue to be used for clinical purposes
†There is lack of agreement about the ideal waist cut off points for Japanese. The best correlates with visceral fat are a waist of 85 cm in males and 90 cm in females. However the best agreement with CVD and diabetes risk factors are 90 cm and 80 cm respectively. Further work is required to resolve this problem.
Step 3: Intervention to prevent the development of type 2 diabetes
There is substantial evidence that lifestyle changes (achieving a healthy body weight and moderate physical activity) can help prevent the development of type 2 diabetes and should be the initial intervention for all people at risk.
Obesity, particularly abdominal obesity, is central to the development of type 2 diabetes and related disorders. Weight loss improves insulin resistance, hyperglycaemia and dyslipidaemia in the short term, and reduces hypertension. Overweight and obese people should therefore be encouraged to achieve and maintain a healthy body weight. A structured approach such as that taken during the Diabetes Prevention Program (DPP), can produce long-term weight loss of 5-7% of baseline body weight.
Increased physical activity is particularly important in maintaining weight loss. Regular physical activity also improves insulin sensitivity; reduces plasma levels of insulin in people with hyperinsulinaemia; improves dyslipidaemia and lowers blood pressure. Moreover, physical activity increases metabolically active muscle tissue and improves general cardiovascular health. Increased physical activity also reduces the risk of type 2 diabetes.
IDF recommends a goal of at least 30 minutes of moderate physical activity (eg brisk walking, swimming, cycling, dancing) on most days of the week. Regular walking for at least 30 minutes per day reduces diabetes risk by 35-40%. This can comprise several bouts of activity adding up to 30 minutes.
Some people, including those with a high level of risk of developing diabetes who cannot change lifestyle sufficiently, will also require pharmacotherapy. However, they should be encouraged to still maintain lifestyle changes, as they will continue to deliver long-term health benefits. IDF recommends that when lifestyle intervention alone has not achieved the desired weight loss, and/or improved glucose tolerance goals, as set by the health-care provider, metformin in the dose of 250 - 850 mg bid (depending on tolerance) should be considered as a diabetes prevention strategy (particularly in those aged less than 60 years with a BMI greater than 30 (greater than 27 in certain ethnic populations) and a FPG of 110 mg/dl) who do not have any contraindications.
The IDF consensus group awaits with interest the results of ongoing studies using newer therapies.