With type 1 diabetes, the immune system destroys the cells that make insulin, and from then on the patient is the factory. They measure blood sugar before a meal, work out a dose, inject it, and do the arithmetic again at the next meal. At night they wake to check, because a dose that was slightly too large can drop blood sugar while they sleep.

A trial at the University of Chicago reports that all 12 of its participants have potentially been cured, according to NBC News. The treatment transplants islet cells. Islets are the small clusters of cells in the pancreas that sense blood sugar and release insulin in proportion, which is the job the patient has been doing by hand.

A cure for this disease has one practical meaning. The body measures its own sugar and doses itself, and the person stops injecting. That is what the transplant is built to restore. It puts working cells back in the loop, so the sensing and the dosing happen in the same place again, with no arithmetic.

The word "potentially" matters here, and so does the number. Twelve people is a trial, not a treatment, and the reporting available today does not say how long each participant has been followed. Nor does it spell out what drugs, if any, they take to keep the immune system from attacking the new cells. That second question carries weight because the immune system that destroyed the original islets is the same one that would see the transplanted ones. Islet transplants have conventionally relied on drugs that suppress it, and a person who swaps insulin for those drugs has traded one daily burden for another.

So the result to read for is the follow-up. Cells that work at the first check-up and still work after years are a cure. Cells that work for a few months are a long holiday from injections. The trial's later reports will say which of those the 12 have.

Until they do, anyone with type 1 diabetes still sets the alarm for 3 a.m. and reaches for the meter.