Our Allostatic Overload piece already named HbA1c as one of the five markers in the most credible attempt yet to standardise allostatic load. It's worth its own closer look, because the mechanism behind it is a genuinely useful window into how stress stops being a feeling and starts being biology, in a way that wearables and vagal tone only partly capture.
What HbA1c actually measures
HbA1c reflects your average blood glucose over roughly the previous two to three months. Unlike a single finger-prick reading, it can't be skewed by what you ate this morning. That slowness is exactly what makes it useful for this conversation: it's a marker built for tracking sustained patterns, not single bad days.
The mechanism connecting stress to this number
The pathway is well established in the broader chronic stress literature. Prolonged activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system increases cortisol and catecholamine release, which in turn promotes glucose production by the liver and reduces how effectively your cells respond to insulin. Reviews on the topic also point to a second route: chronic stress raises inflammatory signalling, including IL-6, which independently interferes with insulin signalling.
Studies specifically comparing burnout to non-burnout physicians have found meaningfully higher fasting glucose and HbA1c in the burnout group, alongside elevated cortisol and ACTH, with moderate correlations between the two.
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Six biomarker systems, a reflective self-check, and the lab targets to raise with your clinician.
What this is actually useful for
Not diagnosis. Trajectory. HbA1c sitting in the standard range (roughly 4.0 to 5.6 percent) doesn't rule out that you're running on empty, and a rise doesn't automatically mean burnout rather than diet, sleep, or another medical cause entirely. What it's genuinely good for is being one more data point, alongside how you're sleeping, your HRV trend, and how you actually feel, that your doctor can track over time rather than interpret in isolation.
If you already get routine bloodwork, it's worth simply asking to see this number and tracking it across visits, the same way we'd suggest watching HRV as a multi-week trend rather than a single reading. One number, taken alone, tells you very little. The same number, watched over a year during a genuinely demanding period, tells you something worth paying attention to.
Sources
Findings referenced above draw on a 2019 case-control study of physician burnout published via PubMed Central, a 2025 Frontiers in Psychology scoping review on chronic stress and burnout biomarkers, and a 2025/2026 literature review on chronic stress, insulin resistance, and HbA1c mechanisms.
Start with a baseline
The Burnout Biomarker Checklist
A 13-page evidence review covering six biomarker systems, a reflective self-check, and the specific lab targets to raise with your clinician. Free.
Start with the Self-Check on page 11. It takes about four minutes.
The Capio Initiative is an educational and resilience-training platform. We are not a medical practice. The topics discussed are for physiological understanding and burnout recovery, not diagnostic criteria for medical disease. Speak with a qualified healthcare professional before changing anything about your recovery, training, or use of tracking hardware.
