Management of Patient with GMI of 6.8
A GMI of 6.8% indicates excellent glycemic control that is already below the standard target of <7%, and no treatment intensification is needed—instead, focus on maintaining current therapy and monitoring for potential overtreatment or hypoglycemia risk. 1
Understanding the GMI Value
- A GMI of 6.8% approximates an A1C of 6.8%, which corresponds to an estimated average glucose of approximately 147 mg/dL 1
- The American Diabetes Association recommends an A1C goal of <7% (<53 mmol/mol) for many nonpregnant adults, making this patient already at target 1
- GMI is a calculated value from continuous glucose monitoring (CGM) that approximates A1C but is not always equivalent to laboratory A1C 1
Key Clinical Caveat About GMI Accuracy
- GMI performs poorly as an estimate of HbA1c in many patients, with 36-43% of patients showing an absolute difference ≥0.5 percentage points between actual HbA1c and GMI 2
- GMI was derived primarily in young adults with type 1 diabetes and may be particularly unreliable in patients with type 2 diabetes 2
- Device-specific differences exist, with GMI significantly underestimating glycemia at higher HbA1c ranges and potentially overestimating at lower ranges 3
- It is preferable to use CGM mean glucose rather than converting to GMI when making clinical decisions 4
Recommended Management Approach
Maintain Current Therapy
- Continue current diabetes medications without intensification, as the GMI is already below the standard target of 7% 1, 5
- The American Diabetes Association suggests that patients at this glycemic level may even qualify for deintensification of therapy if on multiple medications, particularly hypoglycemia-causing agents (insulin, sulfonylureas, or meglitinides) 1
Assess for Overtreatment Risk
- Evaluate whether the patient is on hypoglycemia-causing medications and consider deintensification or switching to medication classes with lower hypoglycemia risk 1
- Check time below range (TBR) metrics: goal is <4% for time <70 mg/dL and <1% for time <54 mg/dL 1
- If TBR goals are not met, deintensify or modify therapy immediately 1
Verify with Laboratory A1C
- Obtain a laboratory A1C measurement to confirm the GMI estimate, as GMI can differ from actual A1C by ≥0.5 percentage points in up to 43% of patients 2
- Certain conditions such as hemolysis, blood loss, or hemoglobin variants can affect A1C reliability and should be considered 6
Monitoring Strategy
CGM Metrics to Review
- Ensure adequate CGM wear time: >14 days with 70% active time for valid data 1
- Target time in range (TIR) >70% (70-180 mg/dL) for most adults 1
- Monitor glucose coefficient of variation (CV): goal ≤36% to assess glycemic variability 1
- Prioritize reviewing mean glucose directly rather than relying solely on GMI 4
Follow-up Schedule
- Continue regular monitoring of A1C every 3-6 months to ensure continued glycemic stability 5, 6
- Reassess glycemic goals based on individualized criteria including disease duration, life expectancy, comorbidities, and hypoglycemia risk 1
Important Clinical Pitfalls to Avoid
- Avoid intensifying therapy based solely on GMI without confirming with laboratory A1C, as this increases risk of hypoglycemia without clear benefit 5, 2
- Do not pursue further A1C lowering from 6.8% to lower levels unless it can be achieved safely without frequent or severe hypoglycemia 1
- Starting or intensifying insulin at a GMI of 6.8% would lead to unnecessary treatment burden, weight gain, and hypoglycemia risk 5
- The absolute risk reduction of lowering A1C from 6.8% to lower levels becomes much smaller compared to potential risks 1, 6
Special Population Considerations
- In elderly patients or those with limited life expectancy, a GMI of 6.8% may actually be lower than their individualized target, warranting consideration of less stringent goals 1, 5
- For patients with high hypoglycemia risk, frailty, or significant comorbidities, less stringent goals (such as <8%) may be more appropriate 1