Sinai Health Magazine

Fall 2019 | The Changing Face of Diabetes

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Dr. Bernard Zinman

Interview: Dr. Bernard Zinman

Renowned endocrinologist Dr. Bernard Zinman, C.M., an honouree of the new Sinai 100 Chairs campaign, shares insights from his decades-long career treating and studying diabetes.

In 2023 — just two years after the world celebrates the 100-year anniversary of the discovery of insulin right here in Toronto — Mount Sinai Hospital will mark its 100th anniversary. As part of the celebrations, Sinai Health Foundation is honouring the doctors and scientists whose achievements have elevated our reputation for world-class care by launching a campaign to establish a select number of prestigious, endowed Sinai 100 Chairs. The Chairs will help recruit and fund the work of the next generation of preeminent Mount Sinai clinicians and scientists, securing the next century of caring and discovery at Sinai Health.

Each Sinai 100 Chair will carry the name of one of Mount Sinai’s most eminent trailblazers, including internationally renowned, Montreal-born endocrinologist Dr. Bernard Zinman, who has helped significantly improve the way diabetes is treated across the world — a major accomplishment given that it’s expected some 500 million people globally will have the disease by 2025.

For more than four decades, Dr. Zinman, Stephen and Suzie Pustil Diabetes Research Scientist and Senior Investigator at the Lunenfeld-Tanenbaum Research Institute (LTRI), has studied diabetes. He says he’s most proud of his work as a clinician helping patients manage their diabetes and reduce complications, and of his leadership role in two studies that have changed clinical care. One is the ongoing and pivotal U.S.-Canada Diabetes Control and Complications Trial (DCCT), the largest and most comprehensive type 1 diabetes complications study ever conducted. In 1993, the DCCT proved that in type 1 diabetes, keeping blood glucose levels as close to normal as possible slowed the onset and progression of eye, kidney and nerve complications. It is the most-cited type 1 diabetes study ever undertaken. More recently, Dr. Zinman led a study that reported in 2015 that in type 2 diabetes a new therapy called SGLT 2 inhibitors improved glucose control, lowered blood pressure and also reduced cardiovascular death by 38 per cent and overall mortality by 32 per cent. They have since become the treatment of choice for people with diabetes who have cardiovascular or kidney complications.

Dr. Zinman is confident that 100 years from now, “we’ll have a much better understanding of the mechanisms of disease, the diversity in how diabetes presents and how people’s responses to treatment can vary substantially. We’ll be able to precisely diagnose the medical problem and provide personalized approaches to managing that condition based on genetics and looking at various biomarkers predictive of diabetes progression and complication risk.” A lot of this, he believes, will come from physician-scientists working with artificial intelligence “to help us provide more precision in diagnosis and management.”

"It’s almost 100 years since the discovery of insulin and a cure remains elusive."

Meanwhile, says Dr. Zinman, Sinai Health will continue to play a significant role in that evolution. “It will continue to value clinician-scientists, people who not only do a great job in managing a particular condition but are also involved in the discovery of new treatments and insights into diseases and their underlying causes. We will increasingly become what I like to call “a research-based hospital” providing the best care, and, most importantly, discovering innovative approaches to disease prevention and treatment which will have a national and global impact.”

Philanthropy, he notes, will continue to play a key role in that work, as it has in his own research. “Philanthropy is an important part of the engine to move academic pursuits forward,” Dr. Zinman notes. “To complement the role of standard, government-run agencies, we need more organizations that are prepared to fund innovative and high-risk research that are not funded by traditional agencies. We also need individuals who want to give back to the community, and one way of doing that is through supporting health research.”

Here, Dr. Zinman reflects on how the field of diabetes has changed over the course of his career, and what he’s learned from caring for patients.

Q: Canada — and Toronto specifically — is considered the epicentre of diabetes research. Why is that?

BZ: The discovery of insulin in 1921 by Drs. Frederick Banting, Charles Best, James Collip and John MacLeod led to Canada’s first Nobel Prize. It put Canada on the map with respect to diabetes, and many of us in subsequent generations have endeavoured to not only maintain that preeminence but expand it. And so, today, Canada punches well above its weight in clinical and basic diabetes research, in addition to state-of-the-art clinical care.

Q: You have been a clinician-scientist in the field of diabetes for more than 40 years. What did we know about diabetes when you first began working in the field?

BZ: Our knowledge of diabetes was quite limited, actually. We knew there was a difference between type 1 and type 2. We had a limited understanding of how to prevent the long-term complications of diabetes. We had poor therapies that were associated with hypoglycemia and weight gain. Our insulins were at a very early stage of development and not duplicating physiologic patterns of insulin secretion by the pancreas. We were just starting to experiment with insulin pumps, and now they’re part of standard clinical care.

Q: Starting out, did you think there would be a cure by now?

BZ: Usually I’m very optimistic, but in this area I was a little skeptical. It’s almost 100 years since the discovery of insulin and a “cure” remains elusive. We’re far better off now but certainly not at the end of the quest to conquer diabetes. When one talks about a cure, you have to look at type 1 and type 2 diabetes differently. Type 1 diabetes results from an immune destruction of the beta cells of the pancreas, so it requires an immune intervention for a cure, and there’s been a great deal of work trying to identify people who are early in the course of the disease and implementing a treatment that would protect the beta cells.

Another cure would be to transplant pancreas or islet cells back into a person who has type 1. Unfortunately, even if it’s a transplant from a twin who is genetically identical, these cells are destroyed by the ongoing autoimmune beta-cell destruction. So a lot of research is focused on figuring out ways to protect the transplanted insulin-producing cells. The other cure in type 1 diabetes would be to provide an artificial pancreas. Insulin pumps and glucose sensors that take the place of injections have improved dramatically, so a fully automated system duplicating a healthy pancreas would, in essence, be a cure.

As for type 2 diabetes, that’s a different story where prevention is really possible. Type 2 is being driven by the obesity epidemic, and if we could prevent obesity, we’d substantially reduce the epidemic in type 2 diabetes. What is required there is appropriate societal and lifestyle changes in attitudes towards nutrition and exercise; we need to create communities where healthy living is easier to implement with parks, bike trails, better access to healthy foods, better information about nutrition. I don’t think we’ve made enough progress in that area at all — we’re still recovering from the supersizing era.

Q: What’s the most surprising thing we’ve learned about diabetes in your lifetime?

BZ: We’ve learned that although we classify type 1 and type 2 diabetes as separate conditions, there is a great deal of heterogeneity among those groupings. With type 1, there are individuals who present with it as a child, and there are others who are fine until after puberty or middle age. Type 2 diabetes is even more varied, with multiple genetic contributors interacting with environmental factors. A certain group of people may have one component of the metabolic abnormality more prominent than another group. So, for instance, you can have just type 2 diabetes and high blood sugar, or you can have diabetes, high triglyceride, fatty liver and several other metabolic abnormalities associated with type 2 diabetes.

Q: What’s the biggest challenge we face in treating diabetes?

BZ: Our biggest challenge is making sure that the patient is educated and informed, and works with the health-care team, incorporating advice from dietitians, nurse educators, physiotherapists, physicians, nurse practitioners, psychologists and pharmacists, among others, to optimize their outcome. The patient must accept the responsibility of being at the centre of this health-care team.

Q: What have we learned about the relationship between diabetes and obesity?

BZ: Not everybody with obesity develops diabetes. As a matter of fact, the majority of individuals with obesity do not develop diabetes. You need to have a genetic susceptibility and be exposed to environmental factors to develop diabetes. We’ve also learned that not all obesity is the same. There is central obesity, which means there is too much fat in organs like the liver, pancreas, muscles, whereas other individuals are able to store excessive fat in subcutaneous storage sites. So, certain forms of obesity, such as central obesity, predispose more to someone developing diabetes. In addition there’s frequently a family history of diabetes — this is a perfect example of the interaction between genetic factors and environmental/lifestyle influences.

Today, we can’t change your genetics, but we can change your environment. So, if someone does have the genetic susceptibility, maintaining a lean, active lifestyle will help prevent them from getting type 2 diabetes, or at least delay it.

Of course one of the frightening things about the obesity epidemic is that type 2 diabetes is now occurring in children, particularly children who are from minority populations. For example, South Asian-Canadians, African-Canadians, Hispanic-Canadians. In particular our First Nation communities, when exposed to a “Westernized” lifestyle, have disproportionately higher rates of diabetes several times the national average. We have a program in Sandy Lake, Ontario, that’s been in place since 1993 where we work with residents of Sandy Lake First Nation to improve prevention and management of diabetes in the community, and reduce the impacts of the disease and its complications.

Q: In the news we often hear about rates of type 2 increasing, as you say, due to the obesity epidemic. Are we seeing rising rates of type 1 as well?

BZ: Type 1 diabetes is not increasing to the same extent as type 2, but in certain countries, particularly in northern Europe, there seems to be an increase in the rates of type 1 diabetes.

Q: In your experience as a clinician, what is the biggest misconception about diabetes in the general population?

BZ: Many people don’t realize how serious a disease type 2 diabetes can be. On the other hand, the misconception about type 1 diabetes is that they have a shorter life expectancy. Our current data shows that if you’re able to maintain optimal glucose control, starting early in the course of the disease, there’s no reduction in life expectancy with type 1 diabetes.

Q: What have you learned from caring for patients with diabetes over the course of your career?

BZ: It’s nice to see individuals with diabetes being able to incorporate a healthy lifestyle and appropriate disease management as part of their daily life and to be a person with diabetes, not a “diabetic,” which is an unacceptable term. A person who happens to have diabetes is not defined by their condition and can control the disease and do most anything they want.

Written by Patricia Hluchy | Photo by Dave Chan