Leonard Thompson, a 14-year-old Canadian schoolboy, weighed only 29 kilograms when he was admitted to Toronto General Hospital in January 1922. He had been diagnosed three years earlier with Type 1 diabetes – an illness that, until then, had killed every person who contracted it. But Thompson was about to change medical history.
With his father’s approval, the teenager was selected for an experiment by Frederick Banting and Charles Best, a pair of pioneering diabetes researchers. They injected Thompson with insulin – a hormone produced by the pancreas, responsible for regulating the body’s absorption of glucose from the blood. After one failed attempt, the doctors purified the insulin and tried injecting him again. Then, Thompson’s diabetic symptoms began to disappear. He lived for another 13 years. The doctors were flooded with letters from other diabetes sufferers, pleading for urgent treatment.
This week marks the 100th anniversary of that medical leap. Over the last century, a series of medical developments have transformed the daily lives of patients with diabetes. The last few decades have seen particularly rapid and far-reaching advancements. Now, experts say there are even more exciting possibilities on the horizon – landmarks that could, in rich countries at least, potentially wipe diabetes from the map in decades to come.
“The life of people with diabetes has been absolutely transformed over the last century,” says Martin Rutter, professor of cardio-metabolic medicine at the University of Manchester. “Diabetes was a death sentence, basically. People would last for a few weeks or months. They’d have to restrict their carbohydrate intake… but eventually they would die of insulin deficiency.”
What is diabetes − and how is it caused?
Diabetes is among the UK’s most severe long-term health challenges, affecting about 4.7 million people in the UK, of whom about 10 per cent have Type 1 and 90 per cent have Type 2. It means your body does not produce enough insulin. If left untreated, the level of sugar in your blood would become dangerously high.
Type 1 diabetes is caused by a misfired autoimmune reaction. The immune system essentially attacks itself by mistake, destroying the cells in the pancreas used to make insulin. By the time it is diagnosed, the pancreas is normally already dysfunctional. You cannot control your chances of getting it. After a diagnosis of Type 1 diabetes, you need insulin for the rest of your life.
Type 2 diabetes is often linked to being overweight or inactive. Type 2 patients do not initially need insulin treatment; normally, they can control the condition with their diet. But after several decades, Type 2 patients may need to move on to insulin treatment.
How has insulin changed since 1922?
Leonard Thompson’s survival sent shockwaves around the world but, decades later, diabetes patients still relied on insulin from pigs and cattle. Some doctors had to source dead cows from abattoirs. The treatment was imperfect and some patients suffered allergic reactions.
It wasn’t until 1978 that researchers used E. coli bacteria to produce the first genetically engineered “human” insulin. Later sold under the brand name Humulin, it was almost identical to human insulin and caused fewer unpleasant side-effects.
Even after that development, insulin treatment remained crude, as Dr Rachel Besser, consultant in paediatric diabetes and research lead at Oxford Children’s Hospital, remembers. She was diagnosed with Type 1 diabetes in 1987. “Using a syringe, I would draw up some cloudy insulin and some clear insulin,” she says. “One was shorter acting and one was longer acting. The diet was very, very restrictive – you had to time when you ate with when the insulin reached its peak action.”
Then researchers produced what Dr Besser calls “designer insulins … that last different lengths of time – some of them come on faster or slower”. Some fast-acting insulins begin working just 15 minutes after injection; others take much longer to absorb, but then remain active for as long as 24 hours.
How do you deliver insulin – and how has this changed?
Producing insulin is only half the battle. The other challenge comes in delivering the hormone efficiently into the bloodstream. As late as the Seventies, patients were forced to use methods that would be regarded as crude today. Dr Besser has met patients who used to rely on a reusable glass syringe; sometimes, they had to shave the tip to make sure it was sharp enough to pierce their skin.
The “dial-up” insulin pen, developed in the mid-Eighties, proved a game-changer. These came with cartridges, pre-filled with insulin. Patients would simply dial in the quantity they wanted.
Next came insulin pumps, electronic devices usually worn on belts with the liquid fed into the skin via a cannula. They are usually connected digitally to a remote control. Before the widespread use of continuous glucose monitors, patients would use a daily finger prick to assess their blood sugar levels. Then, they would work out how much insulin they need and type it into their remote control. The pump emits the correct amount of insulin.
What does the future hold for type 1 diabetes patients?
Experts stress that we are currently living through a busy time of diabetes research. Every year, new papers are released, all with the potential to improve the daily lives of patients with diabetes.
Increasingly, Type 1 diabetics in the UK have a continuous glucose monitor (CGM) to read their blood sugar without pinpricks. It looks like a little white disc that is attached to the upper arm and and can be read by passing a smartphone across it.
Perhaps most exciting is the development of the artificial pancreas, sometimes called a hybrid closed loop system. It connects a glucose monitor to an insulin pump. Insulin is delivered automatically, based on blood sugar levels. This eliminates the need for the patient to monitor their blood sugar levels or make adjustments manually.
Last summer the NHS announced that 1,000 diabetes patients will be given an artificial pancreas, as part of a medical trial. If rolled out across the country, the technology could prevent life-threatening hypoglycaemic attacks, the NHS says.
“It’s something people [were] only able to imagine decades ago,” says Prof Rutter. “It’s an absolutely amazing discovery.”
Scientists are also excited about the prospect of immunotherapy, a treatment that re-programmes the immune system so that it no longer attacks insulin-producing cells in the pancreas. The technology is still in its infancy but doctors say that, in decades to come, a young child identified at high-risk of Type 1 diabetes (either due to their family history, or an examination of their cells) could be given the treatment while their pancreas is still broadly healthy. If successful, it would prevent them from ever developing the condition.
“Immunotherapies would be a major shift in the way we treat type 1 diabetes – tackling its root cause for the first time,” explains Dr Faye Riley, senior research communications officer at the Diabetes UK charity. “They could be used to prevent new cases of type 1 diabetes altogether and to protect beta cells, halting the progress of type 1 diabetes in those already diagnosed.”
Experts note, however, that most of these impressive medical developments have only benefited patients in high or middle-income countries. In poor countries, hundreds of thousands die each year because they can’t get access to insulin.