Insulin and the First Insulin Pump: How Yale Advanced Diabetes Care

At the beginning of the 20th century, diabetes—particularly what we now call type 1 diabetes—was frequently a death sentence. Children and young adults diagnosed with the disease often survived only months. Treatment consisted of extreme calorie restriction, sometimes called “starvation diets,” which temporarily delayed complications but could not stop them.

The discovery of insulin in 1921 by Frederick Banting and Charles Best of the University of Toronto transformed that reality. For the first time, physicians could lower dangerously high blood glucose and reverse life-threatening metabolic crises. Yet early insulin therapy remained imprecise. Doses were estimated. Blood sugar could be measured only intermittently. Patients often experienced dangerous swings between high and low glucose levels.

The question that followed insulin’s discovery was not whether it worked—but how to deliver it in a way that more closely mimicked the body’s natural regulation.

In the late 1970s, Yale researchers Robert Sherwin, MD, and William Tamborlane, MD, sought to answer that question—how to deliver insulin in a way that truly mirrored normal pancreatic function.

Their inspiration came from an unexpected source. A colleague at Yale was using a portable infusion pump to treat children with iron overload caused by repeated blood transfusions. Sherwin and Tamborlane recognized that the same continuous-infusion technology might be adapted to deliver insulin.

The body normally releases insulin continuously in small amounts, with additional bursts at mealtimes. Standard insulin injections could not replicate that pattern. Sherwin and Tamborlane hypothesized that continuous insulin infusion might better stabilize blood glucose levels and reduce metabolic variability.

Working with engineers and colleagues, they developed one of the first portable insulin pumps—an external device that delivered insulin steadily through a small catheter placed under the skin. Early versions were bulky and worn like a backpack, but the concept was transformative: insulin could be delivered continuously, in a way that more closely resembled normal physiology.

In 1979, the team tested their prototype in children with type 1 diabetes at Yale–New Haven Hospital. Physicians monitored the patients closely overnight, adjusting infusion rates in real time. Blood glucose control improved dramatically—offering early proof that continuous subcutaneous insulin infusion could safely stabilize diabetes. The work helped establish insulin pump therapy as a viable long-term treatment.

As insulin pump technology advanced, Sherwin and Tamborlane were also reshaping the scientific understanding of diabetes management.

Sherwin’s laboratory demonstrated that near-normal blood glucose levels could be achieved safely through controlled insulin infusion. Using precise metabolic techniques—including the hyperinsulinemic-euglycemic clamp, a method that measures how effectively the body responds to insulin—his team clarified how insulin acts in the body and how the brain responds to falling glucose levels. These studies defined both the promise and the risks of intensive insulin therapy.

Tamborlane extended this work into clinical practice, particularly in children and adolescents with type 1 diabetes. As a principal investigator in the landmark Diabetes Control and Complications Trial (DCCT), he helped demonstrate that intensive insulin therapy—through multiple daily injections or insulin pump use—significantly reduced long-term complications such as retinopathy, kidney disease, and neuropathy.

The findings were definitive: tight glucose control changed the long-term course of the disease.

Yale’s participation in the DCCT and related studies helped establish intensive insulin therapy as the standard of care and reinforced the importance of technologies that made precise control safer in everyday life.

The first insulin pumps laid the foundation for what followed. Over time, pumps became smaller, more precise, and easier to use. Today’s models are about the size of a smartphone and can be paired with continuous glucose monitors (CGMs)—small sensors placed under the skin that measure glucose levels in real time.

By integrating CGMs with pumps, researchers and engineers developed automated insulin delivery systems—sometimes called “artificial pancreas” systems—that continuously adjust insulin doses based on live glucose data. These advances have improved safety and stability for many patients, contributing to lower rates of diabetic ketoacidosis (DKA), fewer episodes of severe hypoglycemia, and reduced hospitalizations.

What began as an effort to mimic the pancreas more closely has evolved into a data-driven system that supports safer, more precise long-term diabetes management.

Today, Yale’s work in diabetes spans basic science, clinical trials, and population health.

Investigators are studying how genetic variation influences insulin secretion and sensitivity, aiming to personalize treatment strategies. Others are examining how early metabolic changes predict disease progression, with the goal of intervening before irreversible damage occurs.

Clinical research continues to test novel medications, combination therapies, and device-based approaches that automate insulin delivery. Efforts in prevention focus on identifying individuals at high risk for type 2 diabetes and implementing targeted lifestyle and pharmacologic interventions.

From the first portable insulin pump to automated delivery systems, Yale’s work has helped transform diabetes from a fatal diagnosis into a manageable chronic condition and continues to make diabetes management more precise, personalized, and preventive.