Dan Drucker, Joel Habener, Jens Juul Holst, and Svetlana Mojsov

Powerful new weight-loss drugs became one of the biggest health stories over the past year—and Drs. Jens Juul Holst, Joel Habener, Svetlana Mojsov, and Daniel Drucker played key roles in making these medications possible. The scientists conducted early research starting in the 1970s on glucagon-like peptides, or GLPs, which first transformed diabetes treatment and now obesity treatment.

As with many groundbreaking medical advances, it was a group effort. Holst, at the University of Copenhagen (where he’s now a professor of endocrinology and metabolism), noticed after intestinal surgery that patients’ insulin levels soared while their blood-sugar levels dropped; he attributed the changes to several gut hormones, including glucagon made in the pancreas. Around the same time, Habener (now a professor of medicine at Harvard Medical School and Massachusetts General Hospital) and Drucker worked with animals in the lab at Massachusetts General Hospital and identified new types of glucagon hormones they called GLP-1 and GLP-2. Mojsov, a chemist two floors away, also independently identified the active part of GLP-1, which is mimicked in the new weight-loss drugs like Ozempic and Wegovy (made by Novo Nordisk), and one of two main compounds in Mounjaro and Zepbound (made by Eli Lilly). Mojsov (now a research associate professor at Rockefeller University) produced large amounts of the peptide and developed antibodies to attach to them. The trio eventually collaborated on critical scientific papers that described the active part of GLP-1 in rat guts, and documented that increasing GLP-1 levels corresponded to increasing insulin levels.

Decades later, that understanding led to today’s revolution in diabetes and obesity treatments, which appear to be only the beginning for GLP-1 based medicines. The drugs have been approved to reduce the risk of heart disease, and researchers are studying them as potential therapies for kidney and liver disease, brain conditions like Alzheimer’s, and many more. “I don’t pretend that GLP-1 medicines will work for every single condition for which they are being studied,” says Drucker, now a professor of medicine at Lunenfeld-Tanenbaum Research Institute at the University of Toronto. “But if they show benefit for even half of these conditions, then that will be a tremendous win for people struggling with them.”