The History and Future of Blood Glucose Monitoring

Looking back
It wasn’t that long ago that home blood glucose monitoring wasn’t possible for people with diabetes. The first forays into potential home meters began in the late ’60s and early ’70s, but these machines were very complex beasts that required multistep sequences to obtain a reading that only yielded a very approximate range. In the case of the first “Ames” meter, the user had to match a strip to a color chart, but only after applying a droplet of blood, waiting a precise 50 seconds, then washing off the blood droplet with warm water. There was also a multistep process for preparing the strip before that droplet of blood was applied. A later model replaced the color chart with a needle that would indicate a more accurate range, but it was still not something most people used at home.

The first easy-to-use home glucose meters really didn’t arrive on the scene until around 1981 with the Glucometer and a few others. These meters used the same basic process we still use today, in which blood is exposed to an enzyme (the two main types being glucose oxidase and glucose dehydrogenase — the latter being a little more accurate but also more prone to interfering reactions with other substances). Once the blood is exposed to this enzyme, it oxidizes (loses electrons), and it is then passed through an electrode, which reads the current, which is proportional to the amount of oxidized glucose. The more glucose is in the blood sample, the higher the oxidation will be, causing a higher current, and hence a higher number. This is where coding comes into play — something I talked about in last week’s blog entry.

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Over the years, the instruments have become better and better, and the ability to control the consistency of the enzymes in the test strips has greatly improved, leading to increased accuracy. As you might recall from last week, the increase in the consistency of the enzymes is what has allowed some meters to do away with coding (nope, I’m not gonna elaborate — you’re just going to have to read my entry from last week…).

Fast forward to today
One of the biggest advances in recent years has been the introduction of continuous glucose monitors (CGM). These devices give a continuous readout of glucose levels (well, not completely continuous — most test every five minutes or so, but for our purposes, that’s basically continuous monitoring). However, they measure glucose in a very different (and unfortunately, for the time being, less accurate) way. They measure the glucose in the interstitial fluid between the cells under the skin, rather than the glucose in the blood. The main drawback here is that the interstitial fluid will lag behind blood sugar by about 10–15 minutes. For fasting blood sugars or times when there isn’t much fluctuation, accuracy can be pretty good. But if sugar is surging or falling quickly, these meters can be off in their accuracy. This is why anyone using a CGM still needs to also check sugars with a conventional meter regularly.

Fast forward to the future
It’s always hard to tell where things will go in the future in research terms. Anyone living with diabetes knows there are always a myriad of “hopeful” cures, new approaches, technologies, and other potential improvements to diabetes care. Most of these will not advance to the market — in that long research, development, and testing period, many of them prove impractical, unstable, or simply fail to yield the promise they seem to hold initially.

But there is one line of inquiry that seems to hold some real promise for introduction within the foreseeable future, and that is “tattoo” blood glucose readers. Several years ago, a team from MIT was looking into a very far-out technology that involved injecting special ink made of glucose-responsive carbon nanotubes just under the skin to create a “patch.” When exposed to near-infrared light, it would undergo a color change, which would reflect the user’s blood sugar. Though this sounded promising when introduced in 2010, there has been no recent news from the MIT team on this. But Amay Bandodkar, a nanoengineer at the University of California, San Diego (and his team) have developed a wearable patch that also uses a glucose-responsive ink (through a different process) to give a continuous indication of blood glucose. This device has been tested in human trials and proven to provide results that are just as accurate as traditional fingerstick tests (said trials were done with a very limited sample size, it should be said). Currently, they are working on creating an accompanying meter that can provide a traditional number readout. And the device will likely eventually also communicate with users’ health-care providers via Bluetooth, since we’re officially living in the Star Trek age.

Reasons to hope for the future, and be thankful for the present
I’m generally not one to spend a lot of time and energy thinking about what life with diabetes “will be like X years from now.” I’ve always held the view that the best way to live with this disease is to accept that it may never change and make peace with it. Spending too much energy investing in a future that nobody can predict has always felt like a recipe for angst in the current moment. But in spite of all that, I do believe that 10 years from now, diabetes management will look very different. The advances being made with closed-loop insulin pump/CGM systems, the work being done with “tattoo” glucose meter systems, and the potentials for the entire field of medical nanotechnology in general will transform this disease eventually. Until then, we can be thankful every time we test our blood sugar that we have these amazing little machines that automatically analyze our sugar and reflect it back to us so that we can make better choices and live better lives. We can be thankful every time we inject fast-acting insulin or tell our insulin pump to bolus. We are the beneficiaries of some amazing advances, and our children will be the beneficiaries of even greater achievements.