Diabetes Forecast

Old Dog, New Tricks

By Dave Marrero, PhD ,

I have had type 1 diabetes for more than 30 years, and, like many of you, at each step of the way I have had to use what knowledge was available to adapt to the tasks of daily living. In essence, I created a set of "rules" to achieve a balance between the demands of therapy and an enjoyable lifestyle, and I've modified these rules as new innovations came along. Restrictive exchange diets were replaced by carb counting and a modest intake of sweets. Urine testing gave way to home glucose monitoring and A1C tests; animal source insulin to human insulin and rapid acting analogs; syringes and vials to pens and pumps. Each had an impact on my "rules of the game."

It was a game I thought I was pretty darn good at playing. But it turns out that my rules weren't quite as effective as I believed, and here's how I found out: I tried a continuous glucose monitor. These monitors, also called CGMs, use a glucose sensor under the skin to transmit data to a receiver, which can either be a stand-alone device or integrated into an insulin pump. The system I used takes a reading every minute.

So what did I learn? First, I experience a period of insulin resistance almost every morning where my glucose would rise and be hard to bring back to normal. This is often called the dawn phenomenon since it usually occurs very early in the morning, while most folks are asleep. I had checked myself previously to see if I was experiencing the dawn phenomenon. The standard rule is to wake up at 3 a.m. over several nights and test blood glucose levels. Since I didn't see any rise, I assumed I was OK. What the CGM taught me was that my dawn phenomenon started much later in the morning. This is why sometimes my prelunch glucose reading didn't make sense.

The second thing I learned about was the timing of my premeal insulin. With rapid acting analogs, we are instructed to bolus about 15 minutes before our meals. Many of us alter this rule in a variety of ways: taking it 5 to 10 minutes before the meal, with the meal, and even after the meal. The CGM system showed me in very graphic detail what these different timings do to my post-meal numbers. For me, taking my bolus at least 20 minutes before the meal seems to work best. And that bolus has to be big enough, too: The CGM showed that I was tending to use too little insulin for many of my favorite meals.

Finally, I have learned a lot about what I term "casual grazing." In my office, there always seem to be opportunities to nibble: bowls of mints and candy, leftover muffins and bagels from meetings, a colleague's popcorn. The CGM has shown me that this type of grazing can have a much more significant effect on my glucose than I ever dreamed. This new knowledge makes me much more able to resist the temptation to graze.

In sum, the CGM has taught me a lot about my diabetes—most of all, that I should not be quite so complacent in my rules of the game. And that you can, indeed, teach an old dog new tricks.



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