DM - Screening and diagnosis

Question 1

Criteria that may be used to diagnose DM

Answer 1

• FPG concentration (after 8 or more hours of no caloric intake) ≥126 mg/dL, or
• Plasma glucose concentration ≥200 mg/dL 2 hours after ingesting a 75-g oral glucose load in the morning after an overnight fast of at least 8 hours, or
• Symptoms of hyperglycemia (e.g., polyuria, polydipsia, polyphagia) and a random (casual, nonfasting) plasma glucose concentration ≥200 mg/dL, or
• A1C level ≥6.5%

Question 2

Preferred test(s) for the diagnosis of DM

Answer 2

Glucose criteria (i.e., FPG or 2-h glucose after a 75-g oral glucose load)

Question 3

Should the diagnostic tests be repeated to confirm DM diagnosis?

Answer 3

• Glucose criteria (i.e., FPG or 2-h glucose after a 75-g oral glucose load) are preferred for the diagnosis of DM
  
  • The same test - plasma glucose or A1C measurement - should be repeated on a different day to confirm the diagnosis of DM
• Glucose level ≥200 mg/dL in the presence of DM symptoms does not need to be confirmed

Question 4

How is pre-diabetes identified?

Answer 4

• By the presence of:
  
  • Impaired glucose tolerance (IGT)
    
    • Plasma glucose value of 140 to 199 mg/dL 2 hours after ingesting 75 g of glucose; and/or
  • Impaired fasting glucose (IFG)
    
    • Fasting glucose value of 100 to 125 mg/dL

Question 5

Can we use HbA1C to diagnose pre-diabetes?

Answer 5

• No
  
  • For prediabetes, A1C testing should be used only as a screening tool
  • FPG measurement or an oral glucose tolerance test (OGTT) should be used for definitive diagnosis
• Note:*
• A1C values between 5.5 and 6.4% inclusive should be a signal to do more specific glucose testing

Question 6

Relationship of prediabetes and metabolic syndrome

Answer 6

Metabolic syndrome based on National Cholesterol Education Program IV Adult Treatment Panel III criteria should be considered a prediabetes equivalent

Question 7

Schedule of screening for pregnant women

Answer 7

• Pregnant females with DM risk factors
  
  • At the first prenatal visit for undiagnosed T2D using standard criteria
• All pregnent subjects
  
  • At 24 to 28 weeks’ gestation, all pregnant subjects should be screened for gestational DM (GDM) with a 2-hour OGTT using a 75-g glucose load

Question 8

How is GDM diagnosed?

Answer 8

• FPG >92 mg/dL
• 1-hour post-glucose challenge value ≥180 mg/dL
• 2-hour post-glucose challenge value ≥153 mg/dL

Question 9

How is T1DM diagnosed?

Answer 9

• By the presence of autoantibodies to:
  
  • Glutamic acid decarboxylase
  • Pancreatic islet β cells (tyrosine phosphatase IA-2)
  • Zinc transporter (ZnT8), and/or
  • Insulin
• Note:*
• Some forms of T1D have no evidence of autoimmunity and have been termed idiopathic

Question 10

Any child or young adult with an atypical presentation, course, or response to therapy may be evaluated for:

Answer 10

• Monogenic DM (formerly maturity-onset diabetes of the young)
  
  • Diagnostic likelihood is strengthened by a family history over 3 generations, suggesting autosomal dominant inheritance