Blood Sugar Markers Your Doctor Isn't Checking

If your fasting glucose came back "normal," you might assume your blood sugar is fine. But normal glucose is one of the last things to change. The markers that catch trouble years earlier usually aren't on a standard lab panel — which means problems can build for a decade before anyone notices.

Why Isn't a Normal Glucose Test Enough?

Your body works hard to keep blood sugar in a tight range. When cells start resisting insulin's signal, the pancreas simply makes more insulin to force glucose into cells. Glucose stays normal — but only because insulin is quietly running overtime behind the scenes.

By the time fasting glucose finally drifts upward, that compensation has often been going on for years. Even glucose readings in the upper end of the "normal" range have been linked to higher long-term cardiovascular risk in healthy adults.¹ "Normal" and "optimal" are not the same thing.

What Blood Sugar Markers Should You Ask About?

A handful of markers — most of them inexpensive and widely available — give a far clearer picture than glucose alone:

Fasting insulin. This is the earliest warning signal, often shifting long before glucose does.² Conventional labs rarely run it unless diabetes is already suspected. Many functional practitioners look for a result in the single digits (roughly 2–6 μIU/mL), while the standard "normal" range stretches up toward 25.

HOMA-IR. A simple calculation combining fasting insulin and glucose into a single insulin-resistance score. A value under 1.0 is ideal; above 2.0 suggests insulin resistance is already established.

HbA1c. Your three-month average blood sugar. The functional target sits closer to the bottom of the normal range — around 5.3% or lower — rather than waiting for it to climb toward the 5.7% prediabetes line.

Triglyceride-to-HDL ratio. Pulled from a standard cholesterol panel you may already have. A ratio under 2.0 is the goal; a higher number is one of the most accessible early flags for insulin resistance. ⁴

And the one almost no one has heard of — the AA:EPA ratio. Measured on a red blood cell (RBC) fatty acid test, it compares two fats — arachidonic acid and EPA — to reveal your inflammatory balance. Here's the surprise: a high ratio usually isn't about your diet at all. The most common reason arachidonic acid climbs is that insulin resistance speeds up the body's own pathway for converting everyday omega-6 fats into it — so an elevated AA:EPA is often a direct reflection of insulin resistance, not something you ate. Practitioners like to see it in the single digits — when it climbs into the teens or twenties, it signals the kind of inflammation that travels hand-in-hand with insulin resistance. Improving your omega-3 balance has even been shown to improve insulin sensitivity.⁵

What Do These Markers Mean for You?

Insulin resistance that's caught early is also insulin resistance that responds best to everyday changes — how you eat, how you move, how you sleep, and how you manage stress. Insulin resistance has been shown to predict long-term health outcomes even in people who never develop diabetes,³ so catching it early genuinely matters.

The encouraging part: you don't have to wait until a number turns "abnormal" to act. The earlier you see the pattern, the more leverage you have.

Frequently Asked Questions

Can I have normal glucose and still have a blood sugar problem?

Yes. Fasting glucose is often the last marker to change. Insulin can be elevated for years while glucose still reads normal, which is why fasting insulin and HbA1c add so much context.

What is a good fasting insulin level?

Many functional practitioners aim for a fasting insulin in the single digits, roughly 2–6 μIU/mL, even though the conventional "normal" range goes much higher.

How do I calculate my triglyceride-to-HDL ratio?

Divide your triglyceride value by your HDL value — both appear on a standard cholesterol panel. A ratio under 2.0 is the goal.

Will my doctor automatically run these tests?

Often not — fasting insulin in particular is rarely included unless diabetes is already suspected. You can ask for it specifically, and a wellness consultation can help you decide which markers are worth requesting.

References

1. Bjørnholt, J. V., Erikssen, G., Aaser, E., Sandvik, L., Nitter-Hauge, S., Jervell, J., Erikssen, J., & Thaulow, E. (1999). Fasting blood glucose: An underestimated risk factor for cardiovascular death. Results from a 22-year follow-up of healthy nondiabetic men. Diabetes Care, 22(1), 45–49. https://doi.org/10.2337/diacare.22.1.45
2. DiNicolantonio, J. J., Bhutani, J., & O'Keefe, J. H. (2017). Postprandial insulin assay as the earliest biomarker for diagnosing pre-diabetes, type 2 diabetes and increased cardiovascular risk. Open Heart, 4(2), e000656. https://doi.org/10.1136/openhrt-2017- 000656
3. Ausk, K. J., Boyko, E. J., & Ioannou, G. N. (2010). Insulin resistance predicts mortality in nondiabetic individuals in the U.S. Diabetes Care, 33(6), 1179–1185. https://doi.org/10.2337/dc09-2110
4. Kosmas, C. E., Rodriguez Polanco, S., Bousvarou, M. D., Papakonstantinou, E. J., Peña Genao, E., Guzman, E., & Kostara, C. E. (2023). The triglyceride/high-density lipoprotein cholesterol (TG/HDL-C) ratio as a risk marker for metabolic syndrome and cardiovascular disease. Diagnostics, 13(5), 929. https://doi.org/10.3390/diagnostics13050929
5. Akinkuolie, A. O., Ngwa, J. S., Meigs, J. B., & Djoussé, L. (2011). Omega-3 polyunsaturated fatty acid and insulin sensitivity: A meta-analysis of randomized controlled trials. Clinical Nutrition, 30(6), 702–707. https://doi.org/10.1016/j.clnu.2011.08.013

— Michael Rutherford

This article is for educational purposes only and is not medical advice. It is not intended to diagnose, treat, or prescribe. Always make medical decisions in partnership with a qualified healthcare provider who knows your full history.