For clinicians managing patients at risk for autoimmune diabetes, understanding the nuances of glycemic markers is critical for predicting Type 1 Diabetes progression risk. However, recent research suggests that the standard HbA1c threshold of 5.7% may not be the most reliable indicator for adults. This is because HbA1c naturally increases with age due to non-glycemic factors. Consequently, using a universal cutoff often leads to an overestimation of risk in older populations. Therefore, researchers evaluated whether adjusting these thresholds based on age could provide a clearer clinical picture.

The study analyzed data from over 5,000 autoantibody-positive relatives participating in the TrialNet Pathway to Prevention study. Initially, when using the standard 5.7% threshold, children appeared to have a significantly higher one-year progression risk than adults. Specifically, children with multiple autoantibodies showed a 55% risk, while adults showed only 38%. However, these discrepancies largely disappeared when the research team applied age-adjusted HbA1c models. By accounting for physiological aging, the risk profiles between children and adults became comparable.

Improving Accuracy in Type 1 Diabetes Progression Risk

The research highlights that adults over the age of 30 naturally exhibit higher baseline HbA1c levels. Therefore, a higher threshold of 6.0% (42 mmol/mol) serves as a more pragmatic and accurate marker for this demographic. Furthermore, adopting this higher cutoff allows clinicians to better align adult risk stratification with established pediatric benchmarks. This shift is essential for avoiding unnecessary interventions and reducing patient anxiety in clinical practice.

In contrast, the study found that adults under 30 years of age demonstrated a progression risk profile very similar to that of children. For this younger adult cohort, the standard 5.7% threshold remains highly effective. Consequently, these findings advocate for a more nuanced, age-specific approach to monitoring individuals with islet autoantibodies. By refining these diagnostic thresholds, healthcare providers can ensure that the highest-risk individuals receive timely follow-up and appropriate therapy initiation.

Frequently Asked Questions

Why does the standard 5.7% HbA1c threshold overestimate risk in older adults?

HbA1c levels naturally increase with age even in individuals with normal glucose tolerance. Because the standard 5.7% threshold does not account for this physiological drift, it may incorrectly flag older adults as being at high risk for rapid progression.

What is the recommended HbA1c threshold for autoantibody-positive adults over 30?

The research suggests that a threshold of 6.0% (42 mmol/mol) is more accurate for adults aged 30 and older. This higher cutoff ensures that the Type 1 Diabetes progression risk is quantified similarly across different age groups.

Should the 5.7% threshold still be used for younger adults?

Yes. Data indicates that adults under the age of 30 have a progression risk profile similar to that of children. For this younger population, the standard 5.7% threshold remains a reliable predictor of dysglycemia and future diabetes risk.

Disclaimer: This content is for informational and educational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

Templeman EL et al. Accounting for Age-Related Increases in HbA1c More Accurately Quantifies Risk of Type 1 Diabetes Progression in Islet Autoantibody-Positive Adults. Diabetes Care. 2026 May 06. doi: undefined. PMID: 42090204.

Dubowitz N, Xue W, Long Q, et al. Aging is associated with increased HbA1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA1c diagnostic specificity. Diabet Med. 2014;31(8):927-935.

TrialNet Pathway to Prevention of T1D | Clinical Research Studies Listing. All IN for Health. Accessed May 2026.