Research I am Thinking About

GLP-1s and the Quiet Science of Drug Repurposing

At a recent conference, in a hallway after his presentation, a researcher I deeply respect said "GLP-1 medications may ultimately have a larger impact on human health than penicillin." That's a bold statement. 

Penicillin transformed medicine by turning once-fatal infections into treatable illnesses.Few discoveries have changed the course of human health so dramatically. 

So why would a serious scientist make the comparison? 

Because these medications appear to be doing far more than helping people lose weight. Most of the public conversation begins and ends with weight loss. That is not the conversation happening inside research hospitals and scientific meetings. There, the questions sound very different. Could these medications protect the brain? Reduce heart disease? Slow kidney disease? Improve liver health? Influence addiction? Shape the biology of aging itself?

That's why this topic has stayed on my desk. 

Some of those questions already have answers. Large clinical trials show that certain GLP-1 medications reduce cardiovascular risk in appropriate patients, slow the progression of chronic kidney disease, improve metabolic dysfunction-associated steatotic liver disease (MASLD, formerly called nonalcoholic fatty liver disease, or NAFLD), and treat obstructive sleep apnea in adults with obesity. These are no longer promising theories. They are evidence-based treatments. 

Other questions remain open, which is what makes this moment so interesting. Researchers are studying whether these medications might protect the brain in Alzheimer's and Parkinson's disease. Early studies generated real excitement, larger trials have produced mixed results, and that is exactly how good science works. Ideas are tested, the strongest evidence survives, and the weaker ideas quietly fall away. Scientists are also exploring effects on the brain's reward system, with trials underway in alcohol use disorder, nicotine dependence, and opioid addiction. 

There is a name for what we are watching. Drug repurposing is what happens when a medication developed for one problem turns out to help with others. Medicine is full of these stories. You will recognize many of these: 

Why it's still on my desk: The most exciting part of science isn't having all the answers. It's watching a good question become a better one. Whether GLP-1 medications are ultimately remembered as diabetes drugs, weight-loss drugs, or among the first widely used longevity therapies, we are watching one of the most important scientific stories of our time unfold.

That is worth following.

To Read More 

1. Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. New England Journal of Medicine. 2023;389:2221-2232. (SELECT Trial) Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes - PubMed 

2. Perkovic V, Tuttle KR, Rossing P, et al. Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes. New England Journal of Medicine. 2024. (FLOW Trial) Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes | New England Journal of Medicine 

3. Malhotra A, Grunstein RR, et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity. New England Journal of Medicine. 2024. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity - PMC 

4. Parkinson Study Group. Exenatide Once Weekly Versus Placebo in Parkinson's Disease. The Lancet. 2022, along with ongoing phase 3 GLP-1 trials in Parkinson's disease. Exenatide once a week versus placebo as a potential disease-modifying treatment for people with Parkinson's disease in the UK: a phase 3, multicenter, double-blind, parallel-group, randomized, placebo-controlled trial - The Lancet 

5. GLP-1 medications get at the heart of addiction study GLP-1 medications get at the heart of addiction: study – WashU Medicine