[When HbA1c fails]

Area of Science:

• Clinical Chemistry
• Endocrinology
• Diabetes Management

Background:

• Continuous glucose monitoring (CGM) is increasingly used for diabetes management.
• Accurate HbA1c measurements are crucial for assessing long-term glycemic control.
• Discrepancies between CGM-estimated HbA1c and laboratory values can impact clinical decisions.

Purpose of the Study:

• To highlight potential pitfalls in HbA1c measurement.
• To emphasize the importance of vigilance regarding discrepancies between CGM-estimated HbA1c and venous HbA1c.
• To inform physicians managing diabetes, particularly in primary care settings.

Main Methods:

• Case report.
• Comparison of HbA1c values derived from continuous glucose monitoring (CGM) and traditional venous blood draws.
• Analysis of potential sources of measurement error.

Main Results:

• Potential for significant discrepancies between CGM-estimated HbA1c and laboratory-measured HbA1c.
• Identification of factors contributing to measurement errors.
• Clinical relevance of these discrepancies in diabetes management.

Conclusions:

• Physicians must be aware of and vigilant for HbA1c measurement errors.
• Discrepancies necessitate careful interpretation of glycemic control data.
• Proactive identification and management of measurement errors are essential for optimal patient care, especially with rising CGM adoption.