July 28, 2013
John DiTraglia MD
Dr. Deeb is a smart Endocrinologist who used to practice in Portsmouth, but another casualty of the administration at SOMC, has moved to Jacksonville, Fla. He visited us last Friday though, to give a talk about a new diabetes drug, canagliflozin, (kan” a gli floe’zin; “Invokana” - Janssen) that works in a nifty way that I wish I had thought of.
Diabetes mellitus means honey or sweet excess urine in Latin and Greek, because of the ancient observation that a hallmark symptom of the disease was excessive production of urine that was sweet and attracted ants. This sweet excess urination happens because the elevated levels of sugar in the blood exceed the kidney’s ability to reabsorb it. We know that elevated levels of sugar in the blood are due in turn to a lack of insulin that is necessary for body tissues to acquire the sugar.
In the case of Type 1 diabetes this wasting of sugar and water leads to starvation and dehydration. But in the case of Type 2 diabetes it might be seen as an attempt by the body to dispose of the excess sugar and thereby limit excessive weight gain. Obesity is almost always part of the picture of Type 2 diabetes. In the case of Type 2 diabetes (and probably Type 1 diabetes) the kidney threshold for reabsorbing sugar from the urine adapts and increases to some extent.
Enter canagliflozin. This new drug for diabetes works in the kidney and pushes the threshold back down to normal so that a blood sugar greater than about 100mg percent starts to get lost into the urine. This wastes on average about 400 calories in most Type 2 diabetic patients. That can cause a small weight loss in these patients. Since there is more sugar in the urine there is a higher risk of bacterial and fungal urine infections as diabetics are prone to anyway. Otherwise the drug seems to be pretty safe so far.(1)
You might say if you are treating diabetes properly with diet and exercise and other diabetes drugs, the blood sugar shouldn’t ever get much higher than 100mg percent and so this drug wouldn’t do anything. But that doesn’t seem to happen often in the real world. Also you might say why not just eat 400 calories less of carbohydrates to accomplish the same thing. Well you would have to eat those 400 less calories constantly all day instead of at sporadic meals like humans usually do, to succeed in doing what this drug does.
So indirectly and only as an add on drug, canagliflozin seems to be a help in treating Type 2 diabetes. Given together with metformin patients will average about 5 percent weight loss as an extra bonus. Why didn’t I think of that?
1. Canaglifozin (Invokana) for type 2 diabetes. The Medical Letter 2013; 55:37-9.