What is the next course of action if fasting blood glucose (FBG) results from a glucose meter reader (GMR) indicate prediabetes on different occasions in an asymptomatic individual?

Management of Prediabetes Detected by Glucose Meter Reader

When fasting blood glucose readings from a glucose meter reader (GMR) indicate prediabetes on multiple occasions in an asymptomatic individual, laboratory confirmation with venous plasma glucose testing is necessary before initiating any intervention or treatment plan.

Confirming the Diagnosis

The accuracy of glucose meter readings varies and cannot be used alone for diagnosis of prediabetes. According to the American Diabetes Association's Standards of Care:

1. Verify with laboratory testing:

   • Obtain a laboratory-based fasting plasma glucose (FPG) test 1
   • Consider adding an A1C test and/or 2-hour plasma glucose during a 75-g oral glucose tolerance test (OGTT) 1

2. Diagnostic criteria for prediabetes (must be confirmed by laboratory testing):

   • FPG: 100-125 mg/dL (5.6-6.9 mmol/L) - Impaired Fasting Glucose (IFG)
   • 2-h PG during OGTT: 140-199 mg/dL (7.8-11.0 mmol/L) - Impaired Glucose Tolerance (IGT)
   • A1C: 5.7-6.4% (39-47 mmol/mol) 1

Why GMR Results Alone Are Insufficient

Home glucose meters have limitations that make them unsuitable for diagnosis:

• FDA standards for home-use glucose meters allow for 95% of readings to be within ±15% of the actual glucose value 1
• This means readings can vary significantly from laboratory values, especially in the prediabetes range
• Meters are designed for monitoring, not diagnosis 1

Management Algorithm After Laboratory Confirmation

If prediabetes is confirmed by laboratory testing:

Step 1: Risk Assessment

• Evaluate cardiovascular risk factors
• Screen for complications typically associated with diabetes
• Assess risk of progression to diabetes 2

Step 2: Lifestyle Modification (First-Line Intervention)

• Intensive lifestyle modification is the most effective strategy 2, 3:
  • Weight loss goal of 5-7% of body weight
  • Physical activity ≥150 minutes per week of moderate-intensity exercise
  • Dietary changes focusing on calorie restriction and healthy eating patterns
  • Self-monitoring and motivational support

Step 3: Consider Pharmacotherapy

• Metformin should be considered, especially for:
  • Individuals <60 years old with BMI ≥35 kg/m²
  • Those with FPG ≥110 mg/dL or A1C ≥6.0%
  • Women with history of gestational diabetes 2

Step 4: Monitoring

• Laboratory-based glucose testing every 6-12 months
• Annual screening for diabetes complications
• Regular cardiovascular risk assessment 4

Important Considerations

• Discordant results: If laboratory tests show discordance (e.g., normal FPG but elevated A1C), repeat the test that was above the diagnostic threshold 1, 4
• Borderline results: For values near diagnostic thresholds, follow up with repeat testing in 3-6 months 4
• False readings: Certain conditions can affect glucose meter accuracy, including anemia, high hematocrit, hypoxemia, and certain medications 1

Common Pitfalls to Avoid

1. Relying solely on GMR readings for diagnosis or treatment decisions
2. Failing to confirm prediabetes with standardized laboratory testing
3. Delaying intervention after laboratory confirmation of prediabetes
4. Not considering individual risk factors when determining management intensity
5. Overlooking the importance of lifestyle modification as the cornerstone of treatment

Remember that prediabetes represents a significant risk for progression to diabetes and cardiovascular disease, with approximately 10% of people with prediabetes progressing to diabetes each year 2. Early intervention with lifestyle modification has been shown to decrease the incidence of diabetes by 6.2 cases per 100 person-years over a 3-year period 2.