In my practice as a functional medicine practitioner, I consistently see a frustrating pattern: patients who are doing everything right, yet their lab results leave conventional doctors scratching their heads. Even worse, when conventional reference ranges don’t neatly fit a specific diagnosis, patients are often dismissed.

Consider a case that perfectly illustrates this gap between conventional medicine and root-cause therapy: A client who eats a meticulously clean diet, lifts weights, handles their stress, and boasts a textbook-perfect fasting glucose that consistently sits between 80 mg/dL and 88 mg/dL. By all standard measures, their daily blood sugar control looks pristine.
Yet, their Hemoglobin A1c (HbA1c)—the three-month average of blood sugar—tells a completely different, erratic story. It has bounced around over the years, occasionally climbing as high as 6.4% (the literal doorstep of type 2 diabetes). Their last two readings were a stellar 4.8% followed by a sudden jump to 5.9%.

Frustrated and seeking answers, this client did exactly what they were supposed to do: they went to a conventional endocrinologist. The specialist’s verdict? Because the client was asymptomatic and the fasting glucose looked good, they were simply told not to worry and sent home. No deeper investigation was launched. No one looked at iron status, cellular health, or the actual mechanism behind the numbers.

How can someone with optimal fasting glucose and an exemplary lifestyle have an HbA1c that fluctuates so wildly?
When conventional medicine runs out of answers because there isn’t a disease to medicate yet, functional medicine steps in. My job isn’t to treat a piece of paper or wait for symptoms to appear; it’s to understand the unique physiology driving these numbers.

Here is the exact, deep-dive breakdown of how we solve this medical mystery from a root-cause perspective.
Step 1: Broaden the Lens (The Limits of HbA1c)
The first rule of functional medicine is understanding what a test actually measures. HbA1c measures the percentage of hemoglobin proteins in your red blood cells that have glucose attached to them (glycation).
However, this test assumes a major variable: that everyone’s red blood cells live exactly 120 days. Conventional panels look at the glucose, but they completely ignore the lifecycle of the cell carrying that glucose.
If a client has a clean diet and excellent fasting glucose, a high or fluctuating HbA1c often isn’t a sugar problem at all—it’s a red blood cell lifespan problem.
The High Fluctuation (e.g., 5.9% to 6.4%): If red blood cells live longer than average (say, 140 days), they spend more time circulating in the bloodstream, gathering more glucose like a sponge. This artificially inflates the HbA1c percentage, even if daily blood sugars are low. This is incredibly common in people with unrecognized variations in iron storage, low thyroid function, or specific genetic traits.
The Low Fluctuation (e.g., 4.8%): Conversely, if red blood cells are destroyed or replaced too quickly (high cell turnover), the HbA1c will drop deceptively low because the cells didn’t live long enough to collect much glucose.

To read the full protocol please click on the link below.