Doctors have spent a century measuring the wrong hormone entirely

Ask for a standard blood test and you'll get your glucose level back within days. Ask for your insulin level, and you may discover your own doctor doesn't routinely order it, doesn't know what a healthy number looks like, or isn't sure the lab even offers it easily. Benjamin Bikman argues this isn't an oversight. It's the residue of a hundred-year-old accident of measurement.

The story of diabetes goes back over three thousand years, to an Egyptian medical text describing too great emptying of the urine. Physicians in India later noticed that some patients' urine attracted insects like honey, which is where part of the disease's name comes from, mellitus, Latin for honey-sweet. Every early observation pointed to the same visible symptom, excess sugar pouring out in urine, so diabetes came to be defined by glucose. German scientist Wilhelm Falta proposed in 1931 that type 2 diabetes actually is insulin resistance that has progressed far enough to overwhelm the body's ability to keep blood glucose down, but by then the glucose-first framework was already locked in.

It didn't help that glucose was easy to measure and insulin wasn't. A simple glucose test has existed for about a hundred years. A usable insulin test didn't exist until the late 1950s, and it required handling radioactive material, a breakthrough significant enough to win Dr. Rosalyn Yalow a Nobel Prize. By the time insulin testing became more practical, medicine had already built its entire diagnostic system around glucose.

The problem this creates, according to Bikman, is that insulin resistance can exist for years, even decades, while blood glucose still looks completely normal. That's because the pancreas compensates by producing more and more insulin to force glucose down to a healthy range. Only once that compensation fails does glucose finally rise and get noticed, often long after the underlying problem started. Physician-scientist Joseph Kraft, who spent his career studying this, put it bluntly: people with cardiovascular disease not flagged as diabetic are, in his view, simply undiagnosed. Bikman notes that insulin can predict type 2 diabetes up to twenty years earlier than glucose can.

The fix isn't complicated to describe, even if it's still uncommon in practice: track insulin, not just glucose, and pay attention to how quickly it returns to baseline after a sugary drink, since a slow return signals resistance that a glucose reading alone would miss entirely.

Ask your doctor to add a fasting insulin measurement the next time you have blood drawn, and if insurance won't cover it, look into an inexpensive direct lab test on your own. If you can get both numbers, calculate your HOMA score by multiplying fasting glucose by fasting insulin and dividing by 405 for mg/dL or 22.5 for mmol/L, watching for anything above roughly 1.5. Where you can arrange it, ask about a glucose tolerance test that checks insulin every thirty minutes for two hours, since a level that keeps rising past the first half hour is a warning sign glucose alone won't show you. Keep rechecking over time rather than trusting a single result, because insulin can shift within days long before glucose ever budges.