Management> Type 2 Diabetes>

DEFINITION

• Includes risk factors other than genetic determinants (usually associated with positive family history) for type 2 diabetes (T2DM). See module on "Genetic risk factors for type 2 diabetes" for summary of genetic determinants. 
• Often used to screen for T2DM.

EPIDEMIOLOGY

• American Diabetes Association (ADA) recommends diabetes screening for: 1) asymptomatic persons <45 years old of age who are overweight (BMI>25 kg/m²) with any one of the high-risk factors (see below) for type 2 diabetes; or 2) persons >45 years of age (particularly with BMI>25 kg/m²) every three years or more regularly depending on risk status. (ADA Standards of Medical Care).
• In retrospective study of over 46,000 patients > 20 years without diabetes seen at a large academic physician practice, 66% met ADA criteria for diabetes screening; of these, 11% were <45 years with risk factors (Sheehy).
• 86% of those eligible for screening had 1 or more glucose tests performed; 5% of those tested were diagnosed with diabetes.
• Prevalence of high-risk factors: age >45 years (55%); overweight (52%); hypercholesterolemia (50%); hypertension (26%); vascular disease (6%); high-risk ethnic group (4%); prediabetes (0.4%); polycystic ovarian disease (0.4%)
• High-risk factors associated with greatest yield of new diabetes diagnoses: prediabetes (16%); polycystic ovarian disease (13%); and vascular disease (10%)
• The U.S. Preventive Services Task Force (USPSTF) has recommended diabetes screening for patients with hypertension and hyperlipidemia since 2000; however, in the most recent 2008 update, screening only advised for asymptomatic adults with sustained blood pressure >135/80 mm Hg (USPSTF guidelines).
• Only 26% met USPSTF 2008 criteria for diabetes screening (Sheehy)

DIAGNOSIS

• ADA high-risk factors: physical inactivity (exercising < 3 times a week); high-risk ethnicity (e.g. African-American, Latin American, Native American, Asian American, or Pacific Islander); women who delivered a baby >9 lbs (4kg) or had diagnosed gestational DM; hypertension; high-density lipoprotein cholesterol (HDL-C) < 35mg/dL (0.90 mmol/L) and/or triglycerides >250 mg/dL (2.82 mmol/L); women with polycystic ovarian syndrome; previously identified impaired fasting glucose or impaired glucose tolerance; clinical conditions associated with insulin resistance (e.g. severe obesity and acanthosis nigricans); history of cardiovascular disease. First degree relative with T2DM (i.e. genetic risk factor) is also a criterion. (ADA Standards of Medical Care).
• Abdominal obesity: waist circumference > 40 inches (102 cm) in males, >36 inches (88 cm) in females, or increased waist -to-hip circumference ratio that is >0.95 in Caucasian men and >0.85 in Caucasian women confers higher risk; cut-offs may vary by ethnicity (Chan).
• Other risk factors: older age (Cowie); parity (Nicholson); low (versus moderate) alcohol use (Koppes); cigarette smoking (Willi); also (transiently) stopping smoking (Yeh); stress (Golden); low socioeconomic status particularly among Latin Americans and African Americans (Aviel-Curiel; Schootman); diet (i.e. high-fat, low -fiber, Western diet) (Shai); low magnesium intake (Larsson); soda consumption (Nettleton).
• Chronic environmental exposures: inorganic arsenic in drinking water (Navas-Acien); organophosphate and chlorinated pesticides (Montgomery); bisphenol A (a monomer used to make hard, polycarbonate plastics) and some epoxy resins (Lang).
• Urbanization trends: In Pacific island of Nauru, Pima Indians took on a more Western lifestyle leading to more obesity, and diabetes incidence went from nearly 0 to about 50% (Zimmet). In India, Asian Indians living in rural communities had diabetes prevalence of 2%, increasing to 10% after moving to an urban environment (Ramachandran).

CLINICAL TREATMENT

• Weight loss (~5 - 10%) (Knowler)
• Increase physical activity (>30 minutes at least 3 - 5 days/week) (Knowler)
• Decrease triglycerides and increase HDL with lifestyle modification or medication if needed (see Dyslipidemia module)
• Treat hypertension with lifestyle modification or medication if needed
• Cardiovascular disease prevention
• Eliminate soft drinks and sugary foods from diet
• High-fiber diet
• Smoking cessation, though may transiently increase risk of T2DM (Yeh)
• Stress management

EXPERT COMMENTS

• Modifiable risk factors including obesity and physical inactivity are the strongest environmental risk factors for developing T2DM.
• T2DM can be effectively prevented by lifestyle changes in high-risk persons (~60% risk reduction) as demonstrated in the Diabetes Prevention Program.
• Individuals from high-risk ethnic groups who also have other diabetes risk factors may be particularly vulnerable. 
• Diabetes screening programs can identify individuals with high-risk factors.
• Early risk factor identification and modification is essential for prevention of diabetes.

Basis for Recommendations

• American Diabetes Association; Standards of medical care in diabetes--2010.; Diabetes Care; 2010; Vol. 33 Suppl 1; pp. S11-61;
  ISSN: 1935-5548;
  PUBMED: 20042772
  Rating: Basis for recommendation
  Comments:American Diabetes Association consensus statement describing risk factors for diabetes and criteria for screening in asymptomatic individuals.
  
  

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