Pediatric GLP-1s, Alarming Deficiency Spike

Medicine pills and syringe on table with brown bottle — Photo: Adul10 / Shutterstock

Nearly one out of every six kids taking a GLP-1 drug developed a vitamin or mineral deficiency within a year of starting treatment.

Quick Take

A large claims study found 16.8% of pediatric GLP-1 users developed a nutritional deficiency within one year.
Vitamin D deficiency was the most common problem, showing up in 12.4% of kids studied.
Nutritional anemia and iron-deficiency anemia also appeared at meaningful rates after treatment began.
Only about 5% of these children got dietary counseling in the first 30 days of treatment.

What The Study Actually Found

Researchers looked at national insurance claims data from 2017 to 2022, tracking 2,031 kids ages 10 to 17 who started GLP-1 drugs for weight loss, prediabetes, or type 2 diabetes. None of them had a prior deficiency diagnosis. Within a year, 16.8% developed one anyway, according to the study published through Lurie Children’s Hospital. Vitamin D deficiency led the list at 12.4%.

Nutritional anemia showed up in 1.55% of the kids, and iron-deficiency anemia in 1.44%, according to the analysis. Those numbers sound small next to vitamin D, but anemia in a growing child is not a minor issue. It can slow brain development, sap energy, and hurt school performance. The study’s authors called this risk “underrecognized” in a field focused mostly on pounds lost.

Why Appetite Suppression Cuts Both Ways

GLP-1 drugs work by killing appetite. That’s the whole point for a struggling teenager carrying extra weight. But a child who eats less of everything eats less protein, less calcium, and fewer vitamins too. Dr. Contessa Metcalf noted that reduced intake on these drugs can trigger fatigue, dry skin, hair thinning, brittle nails, muscle weakness, and brain fog. Those are not side effects parents expect to hear about at a weight-loss appointment.

The bigger warning sign here is not the drug itself. It’s the gap in follow-up care. Only about 5% of children received dietary counseling within the first 30 days of starting a GLP-1, and just a quarter got any counseling within six months. A powerful appetite suppressant handed to a growing child with almost no nutritional coaching is a recipe for exactly what this study found.

What The Data Cannot Yet Prove

This is claims research, built from billing codes, not lab results. It cannot prove the drug caused these deficiencies rather than simply revealing ones that were already there. Kids with obesity already run higher rates of vitamin D deficiency before any medication enters the picture, with some studies showing rates near 50% in severely obese children. The GLP-1 signal may partly reflect a population that was already nutritionally fragile.

The study also lacks a matched comparison group of similar children who did not take GLP-1s, so there’s no clean baseline to measure against. It doesn’t break out results by specific drug, dose, or treatment length, and it only tracks one year, leaving longer-term risk unanswered. These are real limits, not reasons to dismiss the finding, but reasons to demand better follow-up studies.

The Response From Doctors Treating These Kids

Notably, nobody in the medical literature is arguing these drugs should be pulled from pediatric use. The pushback runs the other direction: doctors are calling for closer monitoring, not less access. One review describes GLP-1 drugs as “adjuncts—not replacements—for long-term nutrition and lifestyle change,” urging a team approach involving nutrition and endocrinology.

New #research from @LurieChildrens shows that nearly 1 in 6 #pediatric patients were diagnosed with a nutritional deficiency within the first year of treatment, underscoring the need for proactive nutritional management when GLP-1s are prescribed to kids. https://t.co/SznlqbZdpE pic.twitter.com/UvyfrDrAby

— Stanley Manne Children's Research Institute (@ManneResearch) September 23, 2026

The study’s lead author put it plainly, saying the goal is “proactive nutritional management when GLP-1s are prescribed to children, as opposed to waiting until a nutritional deficiency is diagnosed”. That’s a reasonable, common-sense standard. If a drug this powerful is prescribed to a growing child, checking vitamin D and iron levels before and during treatment shouldn’t be optional. It should be routine, the same way a pediatrician checks growth charts at every visit.

Parents weighing these drugs for their kids don’t need to panic, but they do need to ask hard questions. Has bloodwork been checked before starting? Will it be checked again in three months? Is a dietitian part of the plan? The evidence so far says the drugs can work as intended for weight and blood sugar. It also says the medical system built around them is not yet catching up to the nutritional side of the equation, and that gap is on doctors and clinics to close, not on parents to discover the hard way.