What insulin resistance looks like before diabetes

Glucose is the measurement everyone knows and it is a late one. Insulin rises first, for years, keeping glucose in range by working harder.

What is insulin resistance?

Insulin resistance means the tissues respond less to insulin, so the pancreas produces more of it to achieve the same effect. For a long time that works. Glucose stays normal, hemoglobin A1c stays normal, and an annual panel comes back reassuring — while insulin levels are well above where they started.

A fasting glucose of 92 mg/dL tells you the system is still compensating. It does not tell you how much effort that is taking, and only measuring insulin does.

Can insulin resistance cause damage before diabetes?

Nerve injury associated with impaired glucose tolerance and the metabolic syndrome begins during it. That injury preferentially affects the small unmyelinated fibers, and nerve conduction studies are relatively insensitive to it — which is why skin biopsy measuring intraepidermal nerve fiber density has traditionally been used to confirm the diagnosis, and why sudomotor testing is useful non-invasively.

Vascular consequences appear during the same phase. Endothelial function is tightly coupled to insulin signaling in the vessel wall, which is why endothelial markers behave as insulin-resistance markers, and why they sit alongside prothrombotic and pro-inflammatory measures. Arterial stiffness and endothelial function.

How many Americans are metabolically healthy?

Analysis of the National Health and Nutrition Examination Survey for 2009 to 2016 defined optimal metabolic health as optimal waist circumference, glucose and hemoglobin A1c, blood pressure, triglycerides and HDL cholesterol, with no medication for any of them. By that definition, under 12.2% of American adults met it in 2009 to 2016, and under 7% do on the tighter criteria applied after 2021 — so more than nine in ten US adults do not. Fewer than one in three normal-weight adults met it; the figure fell to 8.0% among overweight adults and 0.5% among adults with obesity.

In the Padda Institute patient population the picture is starker still: fewer than 3% of patients overall, and fewer than 1% of chronic pain patients, meet the same definition of metabolic health. Those are practice-reported figures from our own population, not trial outcomes, and individual results vary.

How do you test for insulin resistance?

Fasting insulin alongside glucose and hemoglobin A1c — the single highest-yield addition to a standard panel.
C-peptide and fructosamine, which describe the same process from different angles.
Triglycerides and HDL cholesterol, and lipid particle analysis rather than total cholesterol alone.
Waist circumference, which is part of the definition and takes ten seconds.
Body composition, because normal weight with low muscle mass is a distinct and common pattern.
Sudomotor and vascular measurements, because the consequences appear before the diagnosis does.

The genuinely encouraging part

Every component of that metabolic health definition responds to changes in what people eat, how they move and how they sleep. Not equally, not in everyone, and not overnight — but triglycerides and fasting glucose move within weeks to months, and being able to watch them move is itself part of what makes a change stick.

Frequently asked questions

What are the symptoms of insulin resistance?

Often none you would notice. During the compensating phase, glucose and hemoglobin A1c stay normal and a routine panel looks reassuring. The early consequences are quiet: injury to the small nerve fibers and changes in how blood vessels work begin during this phase, which is why sudomotor and vascular measurements can pick them up before diabetes is ever diagnosed.

How can I know if I am insulin resistant?

A standard panel will not tell you, because glucose stays in range while insulin works harder to hold it there. A fasting glucose of 92 mg/dL says the system is still compensating, not how much effort that takes. Adding fasting insulin to glucose and A1c, along with waist circumference, triglycerides and HDL cholesterol, shows what glucose alone hides.

How do you lower insulin resistance?

By changing what you eat, how you move and how you sleep. Every part of the metabolic health definition responds to those changes. Not equally, not in everyone and not overnight, but triglycerides and fasting glucose move within weeks to months, and watching them move on repeat measurements is part of what makes a change stick.

Is insulin resistance the same as diabetes?

No. Insulin resistance comes first, often by years. The tissues respond less to insulin, so the pancreas makes more of it, and that extra effort keeps glucose and hemoglobin A1c in the normal range. A routine panel looks reassuring while insulin climbs. Glucose is the late signal, and nerve and blood vessel changes are already starting during this compensating phase.

References

Araújo J, Cai J, Stevens J. Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009–2016. Metabolic Syndrome and Related Disorders. 2019;17(1):46–52. doi:10.1089/met.2018.0105
Cortez M, Singleton JR, Smith AG. Glucose intolerance, metabolic syndrome, and neuropathy. Handbook of Clinical Neurology. 2014;126:109–122. doi:10.1016/B978-0-444-53480-4.00009-6