HbA1c and beyond: Metabolic dysfunction and its impact on glycemic control

Rising rates of metabolic dysfunction are contributing to a growing public health crisis. This makes advancement in glycemic control assessment more important than ever.

The Centers for Medicare and Medicaid Services now recognize HbA1c testing as a covered diabetes screening test for Medicare and Medicare Advantage patients. The new rule recognizes that measuring HbA1c along with glucose may improve clinical utility of diabetes screening.¹ This update can make it easier for physicians to order tests and assess diabetes risk.

In this article:

Clinical challenge | Why it matters | Ordering recommendations | Interpreting test results | Next steps | Supporting resources

Clinical challenge: How improved testing expands upon what HbA1c can tell us

According to the CDC, the prevalence of total and diagnosed diabetes among US adults 18 and older has steadily increased from 2001 to 2020.² HbA1c remains the cornerstone for monitoring long-term glycemic control. But it offers only part of the picture.

The growing prevalence of prediabetes and diabetes is largely due to underlying insulin resistance. This can manifest for years prior to a rise in HbA1c that warrants a diabetes diagnosis.

Why it matters: Improving diabetes outcomes

Insulin resistance is reflected as a rise in insulin production as the body works to keep blood sugar normal. This overworks the pancreatic beta cells. The earlier that providers identify insulin resistance, the sooner they can recommend lifestyle changes to help slow, stop, or even reverse progression.

Ordering recommendations

Hemoglobin A1c

• Test code: 496
• CPT^® code: 83036

Cardio IQ® Insulin Resistance Panel with Score

• Test code: 36509
• CPT codes: 83525, 84681

Panel components may be ordered separately; includes:

• Insulin, Intact LC/MS/MS (93103)
• C-peptide
• Calculated IR score

Metabolic Risk Panel

• Test Code: 39447
• CPT Codes: 80061, 82172, 83036, 83525, 84681

Panel components may be ordered separately; includes:

• Cardio IQ® Apolipoprotein B (91726)
• Cardio IQ® Hemoglobin A1c (91732)
• Cardio IQ® Insulin Resistance Panel with Score (36509; includes Insulin, Intact LC/MS/MS [93103], C-peptide, and calculated IR score)
• Lipid Panel, Cardio IQ® (91716; includes Cardio IQ® Cholesterol, Total [91717], Cardio IQ® HDL Cholesterol [91719], Cardio IQ® Triglycerides [91718], Cardio IQ® non-HDL and calculated components)

Interpreting results

Insulin Resistance Panel with Score: A new lens into metabolic health

The CardioIQ^® Insulin Resistance Panel with Score (IRRS) improves assessment of glycemic control. It combines c-peptide and intact insulin, which are co-secreted from beta cells, to provide the probability of a patient’s insulin resistance. The results are based on the following population tertiles³:

• A score less than 33 is optimal and indicates normal insulin sensitivity
• A score of 33–66 indicates an individual has >4-fold greater probability of having insulin resistance*
• A score of greater than 66 indicates an individual has >15-fold greater probability of having insulin resistance*

*Relative to someone with a score less than 33.

The IRRS uses LC/MS/MS technology to identify intact insulin and c-peptide. This improves accuracy and specificity. The approach allows for more precise identification of patients with insulin resistance.

Research shows that the components of the IRRS can identify risk for metabolic dysfunction across a wide range of metabolic conditions.

• 80% of individuals with an intact insulin level >10.5 μU/mL have metabolic dysfunction-associated steatotic liver disease (MASLD)
• 85% of patients with an insulin resistance score >31 have MASLD

Next steps: From test to treatment

Counsel patients with an elevated IRRS on lifestyle changes. These can include

• Increased physical activity
• Weight management
• Adhering to a healthy diet

Also consider pharmaceutical interventions when appropriate. The IRRS may be used to track improvement in insulin sensitivity in those without a history of overt diabetes.

Ongoing research continues to explore the utility of the IRRS in children, adolescents, and pregnant women.⁵

Supporting resources