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Type 2 Diabetes
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Those with impaired glucose tolerance test or impaired fasting glucose, obesity (BMI ≥ 30), hypertension, clinical CVD or women with polycystic ovary syndrome who are obese and certain ethnic groups.
All patients should be screened every 3 years from 55 years of age. This should commence from 45 years of age in those with other risk factors, or from 35 years for certain ethnic group such as the Indian subcontinent or China (B) High risk groups should be screened every year (B)
The USPSTF recommends screening for type 2 diabetes in adults with hypertension or hyperlipidemia. (B)
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Clinical Considerations
- In the absence of evidence of direct benefits of routine screening for type 2 diabetes, the decision to screen individual patients is a matter of clinical judgment. Patients at increased risk for cardiovascular disease may benefit most from screening for type 2 diabetes, since management of cardiovascular risk factors leads to reductions in major cardiovascular events. Clinicians should assist patients in making that choice. In addition, clinicians should be alert to symptoms suggestive of diabetes (ie, polydipsia and polyuria) and test anyone with these symptoms.
- Screening for diabetes in patients with hypertension or hyperlipidemia should be part of an integrated approach to reduce cardiovascular risk. Lower targets for blood pressure (i.e., diastolic blood pressure <80 mm Hg) are beneficial for patients with diabetes and high blood pressure. The report of the Adult Treatment Panel III of the National Cholesterol Education Program recommends lower targets for low-density lipoprotein cholesterol for patients with diabetes. Attention to other risk factors such as physical inactivity, diet, and overweight is also important, both to decrease risk for heart disease and to improve glucose control.
- Three tests have been used to screen for diabetes: fasting plasma glucose (FPG), 2-hour post-load plasma glucose (2-hour PG), and hemoglobin A1c (HbA1c). The American Diabetes Association (ADA) has recommended the FPG test (>126 mg/dL) for screening because it is easier and faster to perform, more convenient and acceptable to patients, and less expensive than other screening tests. The FPG test is more reproducible than the 2- hour PG test, has less intraindividual variation, and has similar predictive value for development of microvascular complications of diabetes. Compared with the FPG test, the 2-hour PG test may lead to more individuals being diagnosed as diabetic. HbA1c is more closely related to FPG than to 2- hour PG, but at the usual cut-off points it is less sensitive in detecting lower levels of hyperglycemia. The random capillary blood glucose (CBG) test has been shown to have reasonable sensitivity (75% at a cut-off point of >120 mg/dL) in detecting persons who have either an FPG level >126 mg/dL or a 2-hour PG level >200 mg/dL, if results are interpreted according to age and time since last meal; however, the random blood glucose test is less well standardized for screening for diabetes.
- The ADA recommends confirmation of a diagnosis of diabetes with a repeated FPG test on a separate day, especially for patients with borderline FPG results and patients with normal FPG levels for whom suspicion of diabetes is high. The optimal screening interval is not known. The ADA, on the basis of expert opinion, recommends an interval of every 3 years but shorter intervals in high-risk persons.
Who is at higher risk of type 2 diabetes?
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Who is at higher risk?
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What should be done?
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How often?
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Increased risk
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• Age >55 years
• Women with previous gestational diabetes
• People 45 years of age and over who have a first degree relative with type 2 diabetes
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Fasting blood sugar
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Every 3 years
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High risk
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• Those with impaired glucose tolerance test (IGT) or impaired fasting glucose (IFG)
• Culturally and linguistically diverse groups 35 years of age and over (specifically people from the Indian subcontinent or of Chinese origin)
• People 45 years of age and over who have either or both of the following risk factors:
- obesity (BMI ≥30), abdominal circumference >88 cm females, >102 cm males
- hypertension
• All people with clinical CVD
• Women with polycystic ovary syndrome who are obese
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Fasting blood sugar
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Every 12 months
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Technique
Fasting blood sugar – Measure plasma glucose levels preferably on a fasting sample although a "random" sample is acceptable for screening purposes. The test should be performed by a laboratory rather than by desktop devices as these are less accurate:
< 100 mg/dl (< 5.5 mmol/L) – diabetes unlikely
100 – 124 mg/dl ( 5.5 – 6.9 mmol/L) fasting – perform oral glucose test
126 mg/dl (7.0 mmol/L) or more fasting – diabetes likely, repeat fasting blood sugar to confirm on a separate day
Oral glucose test – 2 hours after a 75 gm oral glucose load is taken orally, the plasma glucose is measured. If this is greater than 200 mg/dl (11.1 mmol/L) diabetes is likely. If it is between 140 and 200 mg/dl (7.8 and 11.0 mmol/L) then there is IGT. If it is less than 140 mg/dl (7.8 mmol/L diabetes is unlikely
Prevention
The target group for the prevention are pre-diabetes (IGT, IFG, gestational diabetes) and those with identified risk factors with negative screening test
- Give advice on healthy low fat diet, weight reduction and increased physical activity
- Refer patients to a dietician and a physical activity program
- Provide pre-conception advice to women with a history of gestational diabetes
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