When blood sugar crashes, a healthy body fights back by releasing glucagon, a peptide hormone that orders the liver to release stored sugar. In children newly diagnosed with type 1 diabetes, that counterpunch is already gone. In a controlled test, kids at diagnosis produced almost no glucagon response to a deliberate low, even though their blood sugar fell further than the healthy comparison group's.
The finding comes from GLUREDIA, a prospective study published August 26 in BMJ Open Diabetes Research and Care ↗ by Aline Harvengt, Philippe Lysy and colleagues across several Belgian centers. They followed 22 children and adolescents, ages 2 to 17, from the moment of diagnosis, with 8 healthy first-degree relatives as a reference. Each child underwent the same standardized insulin-induced hypoglycemia test, in which blood sugar is lowered on purpose under supervision, at diagnosis and again at 6, 12, and 18 months. Healthy participants showed the expected sharp glucagon rise as they went low, a strongly significant effect. The newly diagnosed children showed essentially none.
The alarm does not just fade, it inverts
The trajectory over the next year and a half was not a simple decline. Glucagon responsiveness was absent at diagnosis, flickered back slightly at 6 months, vanished again at 12 months, and by 18 months had gone the wrong way, with glucagon suppressed during hypoglycemia instead of rising. Baseline glucagon, measured when blood sugar was normal, stayed steady the whole time. So the alpha cells that make the hormone were not simply dying off. What broke was the emergency response, the ability to sense a low and answer it.
The study also asked what travels with a working response. Children whose glucagon still answered a low spent more time in the target glucose range and had less glucose swing and fewer hypoglycemia episodes. A model built only from continuous glucose monitor data flagged the children with a broken response reasonably well (area under the curve 0.79, where 1.0 is a perfect test and 0.5 is a coin flip), which raises the possibility of spotting counterregulatory failure without a hospital challenge test. Two gut hormones, GIP and GLP-1 ↗, the same incretins that today's weight-loss and diabetes drugs imitate, correlated positively with glucagon secretion, a hint that broader islet-hormone health moves together.
Why an early defect matters
Impaired glucagon counterregulation is a major reason people with type 1 diabetes can slide into severe hypoglycemia without the internal brake that protects everyone else. The textbook view held that this defect accumulates over years. The Belgian data put it at the start of childhood diagnosis, and show it worsening within eighteen months. That early timing is the news. It reframes severe lows in newly diagnosed kids as a problem of a rescue system that is offline from the beginning, not one that erodes slowly with disease duration.
It is also why glucagon itself is sold as a rescue drug, an injected or nasal peptide given when someone cannot treat a crash on their own. The body's built-in version is failing early in these children, so the external one carries real weight. Glucagon acts through the glucagon receptor ↗, the same receptor that dual and triple agonists now court on purpose; the low it is meant to answer is driven through the insulin receptor ↗. The study is a reminder that the two-hormone balance behind blood sugar breaks on the glucagon side sooner than the field assumed.
The honest limits are size and design. Twenty-two children and eight relatives is a small sample, the 18-month suppression signal rests on the subset who completed every test, and the links between glucose instability and alpha-cell failure are correlations, not proof of cause. This is a natural-history study, not a treatment trial. It maps the problem rather than fixing it. What it changes is the clock: the glucagon rescue reflex in type 1 diabetes is not a late casualty. In children, it is broken almost from the day the diagnosis is made.