By far the techiest of all d-Tech is continuous glucose monitoring, known simply as CGM. It’s so frickin’ high-tech, it borders on magic. It’s the CT scanner of blood glucose testing—it lets you see what’s happening inside your body in a whole new way.
Now, to be honest, CGM is an absolute lie, because it’s not continuous at all. It only tests your blood sugar every five minutes. We should probably call them VCGMs, for virtually continuous glucose monitors. That’s still the equivalent of 288 finger sticks a day, which is a helluva lot of information.
Oh, and contrary to popular belief, CGM doesn’t actually test your blood sugar at all, either. It monitors sugar in the water between your cells. But that water is like a mirror: it reflects blood sugar beautifully.
And speaking of water, the first thing you’ll discover, if you take the CGM plunge, is that your blood sugar is far more fluid than you ever dreamed. It flows uphill and downhill. It meanders. Sometimes, it’s a torrent. At other times, it’s a trickle—but it’s always in motion. By tracking blood sugar readings so frequently and watching the changes from test to test, CGM reveals the motion of this ever-changing river.
Traditional finger sticks are just a static snapshot of this fantastic flood—an isolated moment in time. We are so used to them that we don’t appreciate what a limited worldview they give us. Think about it: what does it mean to know your blood sugar is 148 mg/dL (8.2 mmol/L)?
Not much. Not by itself.
A 148, when your blood sugar is surging upward, tells you something. And a 148 when your blood sugar is cascading downward tells you something else. That’s what CGM gives us: context. And context gives our numbers power. Simply put, it tells us what to do with our numbers. CGM is a compass that helps us navigate our blood sugar river.
On the gear side of the equation, CGM has three parts: a sensor, a transmitter, and a monitor. The sensor is a very thin wire that’s injected under your skin. Don’t freak out. The old-fashioned finger sticks hurt more. The sensor monitors your glucose, and, using the transmitter, beams your numbers wirelessly to the monitor (which may be built into an insulin pump).
In real time, CGM monitors provide alarms that help you manage your diabetes better in the here and now. After the fact, their stored data is downloadable, so we can study cause and effect on our computers—days, weeks, and months later. That lets us see how well our therapy is managing our diabetes. For insulin users in particular, it can help answer the three major confounding questions that face us: is my basal right? Is my insulin-to-carb ratio right? Is my correction factor right?
That’s an amazing sea of information.
Wil Dubois is a diabetes treatment specialist with the Pecos Valley Medical Center in New Mexico, a rural non-profit clinic. He has type 1 diabetes, and is a health columnist and author who has published over 275 articles and four award-winning diabetes books.