'I'm sorry, but your sugar is still too high," I tell my anxious patient, reviewing his blood work. Sathees, a 39-year-old who has had diabetes for six years, has been dreading this moment. But he accepts my verdict, knowing I will prescribe more medication – adding to the five tablets that he's already taking.
For diabetics, this is a typical scenario, repeated thousands of times a day in clinics across Canada. Too frequently, the medications we use to treat diabetes just fade away, losing their sugar-reducing effect.
"Therapies tend to fail over time," says Prof. Bernie Zinman, who spoke recently at a conference at the Li Ka Shing Knowledge Institute, University of Toronto. That's why family docs have to pile on more and more pills in an attempt to prevent diabetes complications – heart, kidney, eye and nerve damage.
"No way," Sathees pleads, "I don't want injections." He hasn't lost weight, shrugs when I ask about regular exercise, and won't cut down on his precious carbs – his daily bread and rice. "Just give me another tablet," he insists.
Fortunately for him, a promising new class of diabetes medications is expected in Canada. (Release dates have been delayed, as regulators have asked for more data from the manufacturers.) These novel pills work in an entirely different way, have fewer side effects, are heart-smart and even promote weight loss. Though the names are unpronounceable – canagliflozin, dapagliflozin, empagliflozin – these new tablets will be a welcome addition to our menu of diabetes medications.
This newest generation of medicines is known as sodium glucose transport-2 (SGLT-2) inhibitors. "These medications use the kidney to excrete excess sugar," explains Dr. Richard Gilbert, chair of Diabetes Complications Research and head of endocrinology at Toronto's St. Michael's Hospital.
How does this work? The kidney is the body's blood filter, working like a pool pump, to remove junk and return cleansed water back into the system. The kidney flushes out waste products into the urine, while recapturing the good stuff – sugar, proteins and other nutrients. The new pills, the SGLT-2 inhibitors, block this reabsorption of sugar. The result? You urinate out sugar, reducing the amount left in your bloodstream.
Remarkably, this promotes weight loss. "These medications help to offload excess calories," says Gilbert. Over time, patients can expect to lose three to five kilograms. That may not sound like much, but it is a paradigm shift. For example, the first-generation pills, known as the SUs, actually cause weight gain.
As with all medications, there are trade-offs. All that sweet water flowing out from the kidney is not without side effects. These new pills do cause a modest increase of bladder and genital infections. The extra sugar concentrated in the urine acts as a banquet for bugs. It also increases urination, "an extra one void [time] per day," explains Gilbert. But generally, these side effects are mild and manageable.
What is particularly valuable is the fact these new agents do not cause sugar-crashes, known as hypoglycemia, which is a dreaded side effect of older diabetes medications. When your blood sugar sinks too low – say, below 4.0 – you start to sweat, tremble and your pulse races. Without ingesting sugar right away, you faint. Several such bad episodes can cause heart attacks. That's why Dr. Subodh Verma, a leading heart surgeon and decorated researcher at the University of Toronto, values the SGLT-2 inhibitors. "We must protect the heart … and these agents have much less potential for hypoglycemic events."
Managing the coming diabetes epidemic won't be easy. Right now, there are three million Canadians with diabetes. Six million more are prediabetic: They are diabetics-in-training, on course to develop the disease with their current lifestyle. There's a whole generation of adolescents who study, play and socialize by computer – a digital world in which physical activity is unnecessary.
That's why the Canadian Diabetes Association released a call to arms, the first Diabetes Charter for Canada, during ceremonies Monday across the country. Like a bill of rights, the charter outlines the duties and responsibilities of patients, health-care providers, governments, schools and the public.
Richard Blickstead, the president and CEO of the CDA, referred in a press release to "specific ethnocultural populations" who have a higher incidence of diabetes. The same day, Peel Public Health published a diabetes atlas tracking the disease in particular neighbourhoods. In Brampton, for instance, people of South Asian and Caribbean backgrounds account for one of the highest rates of diabetes in Ontario. Streetscapes that discourage walking in those neighbourhoods were also named as a contributing factor.
While no single diabetes pill can tame an epidemic, it is vitally important to have an ever-expanding list of treatments. As doctors, we need to prescribe multiple tablets earlier, be more aggressive in controlling sugar and vigilantly screen for organ damage. We anticipate that the SGLT-2 inhibitors will be a significant addition to the cocktail of medications offered to Canadians – and an important piece of the evolving diabetes puzzle.