Debbie Sissmore was four years old when she was diagnosed with type 1 diabetes almost 49 years ago. She was 30, newly married and working as a Grade 2 teacher, when complications of the disease took her sight.
“Now we have better insulins, insulin pumps, carb counting and meters so that you can read your own blood sugar results. The advances in treatment have been extraordinary,” she says. But in those early days, home blood glucose (sugar) testing wasn’t available. She had one insulin injection per day, using a glass syringe.
Ms. Sissmore has brittle diabetes, which means it was extremely difficult to manage her blood sugar. High blood sugar levels over a sustained period of time can lead to the development of diabetes-related complications, including diabetic retinopathy, the leading cause of blindness in Canadian adults. “At the time, I thought that was it – I lost my independence, my career, my goals and my dreams,” she says.
With the support of her husband, the Canadian National Institute for the Blind and her friends and family, Ms. Sissmore rebuilt her life. In addition to volunteering for the Canadian Diabetes Association (CDA), she turned to long-distance running. With a guide holding one end of a towel while she held the other, the guide alerted her to uneven footing, curbs and obstacles. Since then, she’s run countless races and half-marathons, as well as the New York City marathon.
In 2003, she became the 60th person in Canada to have an islet cell transplant. “It saved my life. We’re almost at my 12-year anniversary, post transplant. I take a small amount of insulin today, a fraction of what I used to take, but the most important thing by far is that my blood glucose [sugar] levels have remained in a perfect target range. I’ve maintained excellent control since then, with no further signs of any diabetes-related complications.”
Research has played a significant role in her life, but more is needed, she stresses. “The future is brighter for those living with diabetes now, because of the great tools available. But we have a long way to go. Great research is going on, but we need funding.”
One project of particular promise for the more than 500,000 Canadians with diabetic retinopathy is under way at the Université de Montréal. Dr. Mike Sapieha’s recent CDA-funded research was published in a prestigious “Scientific Show Stopper” article in The Journal of Clinical Investigation.
Dr. Mike Sapieha’s CDA-funded research on diabetic retinopathy was recently published in The Journal of Clinical Investigation.
“The blood vessels that are sick in diabetic retinopathy represent a very low percentage of the cells within the retina – the bulk of the cells are neurons and associated cells called glial cells,” explains Dr. Sapieha, the Canada Research Chair in Retinal Cell Biology and Associate Professor of Ophthalmology at Université de Montréal. “We wanted to know whether these cells could be driving some of the damage.”
Through a series of studies, Dr. Sapieha and his team found that, with diabetes, the nerve cells within the retina produce molecules that are otherwise present at high levels only when the eyes are developing in the womb. “These molecules are a family of proteins called neuronal guidance cues. For example, they ensure that as the brain develops, your little toe will receive the right nerve so you’ll be able to sense when it is being touched.”
In diabetic retinopathy, these molecules increase to abnormal levels. “When this embryonic program becomes reactivated, the vessels open up just a bit. Their junctions are compromised, and then you get the leakage – the edema – associated with diabetic macular edema. We also found that this same protein, semaphorin 3A, can be highly inflammatory.”
With funding from venture capital company AmorChem, Dr. Sapieha and his team are now at work on compounds designed to inhibit semaphorin 3A. “We’re developing inhibitors that seem to work well at preventing diabetic macular edema and the inflammation within the retina that causes new pathological vessels to grow. We’re in the advanced stages of development before going into clinical trials.
“We’re at a very exciting period right now, because we’re able to develop compounds that have a very tangible impact on a disease that affects so many people.”