Your fasting glucose looks fine. It may not be.

METABOLIC HEALTH · NOVEMBER 2026

Fasting glucose misses the problem. Fasting insulin catches it years earlier.

Based on research including Kraft JR, "Detection of diabetes mellitus in situ," Boletin de la Asociacion Medica de Puerto Rico, 1975, and subsequent work by Crofts et al. published in the Journal of Insulin Resistance, 2015 and 2016.

WHAT THE STUDY FOUND

Joseph Kraft spent decades running 5-hour oral glucose tolerance tests with simultaneous insulin measurements. What he found was that a large proportion of people with completely normal fasting glucose had abnormal insulin responses, meaning their pancreas was working far harder than it should to keep glucose in range. He called this "diabetes in situ." The insulin was already elevated. The glucose had not moved yet. By the time glucose rises enough to register as pre-diabetes on a standard panel, the metabolic dysfunction has usually been building for years. If you want a deeper look at how we interpret these patterns at Expand Health, that context is on our site.

WHY IT MATTERS

Standard metabolic screening checks fasting glucose and sometimes HbA1c. Those are lagging indicators. They tell you something has already gone wrong. Fasting insulin, and ideally a full insulin response curve after a glucose load, tells you what is happening before glucose dysregulation becomes visible. That window, is where intervention is easier.

Insulin assays cost more. They are not part of standard panels. Many labs do not reflexively include them, and most GPs do not order them unless glucose is already flagged. So the dysfunction builds quietly, and patients are told they are healthy until they are not.

HOW WE THINK ABOUT THIS AT THE PROTOCOL

In our clinics in Cape Town and Bucharest, we include fasting insulin as a standard part of the metabolic workup. When we look at the full picture alongside HOMA-IR, triglycerides, waist circumference, and sometimes a post-load insulin curve, we regularly see people whose routine bloods look fine but whose insulin physiology is already under significant strain. We aim to close that gap by measuring before prescribing and catching the signal early.

WHAT YOU CAN DO WITH THIS

• — Ask your doctor to add fasting insulin to your next blood panel. It is a simple add-on. A HOMA-IR score (calculated from fasting glucose and fasting insulin together) gives you a cleaner picture of insulin resistance than glucose alone.

• — If you can access a 2-hour post-load insulin test, do it. The shape of the insulin curve after a glucose challenge reveals dysfunction that a single fasting number will not show.

• — Do not interpret a normal fasting glucose as metabolic clearance. It is one data point. Pair it with fasting insulin, triglycerides, and waist-to-height ratio before drawing any conclusions.

THE BIGGER PICTURE

Hyperinsulinemia can precede type 2 diabetes, cardiovascular disease, and some cancers by years. Catching it earlier could prevent many chronic diseases. That shift from reactive to predictive is what P4 medicine is about in practice.

ESTIMATED WINDOW BEFORE FASTING GLUCOSE RISES WHERE FASTING INSULIN IS ALREADY ELEVATED

See how we screen for this →

P.S. Has your doctor ever ordered a fasting insulin test alongside your standard bloods? Hit reply and let me know. I am curious how common that actually is for people reading this.

— Emilian