A standard physical usually checks fasting glucose and stops there. The trouble is that glucose is a lagging signal. The body can keep it looking normal for years by quietly producing more insulin, and by the time glucose finally drifts, the pattern is well underway. HbA1c and fasting insulin read together catch that earlier. Here is what each marker measures and how a physician uses the pair.
What each marker measures (hba1c levels)
HbA1c measures the share of your hemoglobin that has glucose attached to it. Because red blood cells live about three months, that share works as a running average of your blood sugar over that window, not a single fasting snapshot. It smooths out the noise a one-morning glucose draw can carry. Fasting insulin measures something different: how much insulin your pancreas is releasing to hold that sugar steady after an overnight fast. HbA1c tells you roughly where blood sugar has been sitting. Fasting insulin tells you how much effort it took to keep it there, and that effort tends to climb before the sugar itself moves.
What the ranges mean (reference versus optimal)
Reference ranges here are wide and, as always, describe a population rather than you. As rough orientation, HbA1c is often discussed with optimal in the lower end of normal and a prediabetic band commonly cited around 5.7 percent and up, though exact cutoffs vary by lab and guideline. Fasting insulin reference ranges are broader and less standardized, and many discussions of optimal sit well below the top of the lab range. Treat these as orientation, not personal targets. The useful point is that a result can sit comfortably “in range” on both markers and still be drifting over time. That gap between a lab’s reference range and an individual’s optimal range is exactly the judgment that belongs to a physician, not a chart.
you are
Add what fits. Consent happens at checkout, prescriptions come from independent licensed providers, and weight and hormone paths include a consult. Browse the shop →
How they read alongside other markers (insulin resistance markers)
Neither marker is at its best alone, and the pair is far more informative than either one solo. The classic early pattern of insulin resistance is a normal or near-normal glucose held up by a rising fasting insulin, with HbA1c still unremarkable. Glucose alone misses that. Read together, insulin and HbA1c surface it sooner. The picture sharpens next to the rest of a panel: triglycerides and ApoB, since insulin resistance tends to move lipids, covered in the ApoB explainer; and the hormone markers, because high insulin tends to push SHBG down, which changes how testosterone reads. This is the “labs before molecules” idea: you measure the full set first, before anyone discusses whether a protocol fits. (See the Telos Panel and our core hormone and health panel overview.)
What your physician does with this (labs before molecules)
At Telos, the information you provide and the panel you complete are reviewed by a licensed physician through the affiliated medical group. They read HbA1c and fasting insulin together, against your lipids, hormones, history, and goals, and decide what, if anything, fits. This pair is also where a metabolic or GLP-1 conversation honestly starts, since medications like semaglutide and tirzepatide are weighed against a real metabolic baseline, not a single glucose value. The deeper read on that is in the GLP-1 metabolic panel. A physician may or may not establish a treatment relationship. Telos is a marketing and advertising company. It does not practice medicine, prescribe, or dispense. Nothing here is medical advice.