New Test for Diabetics: Medicine's Next Big Thing? -- In Depth Doctor's Interview

Jeffrey Thomas LaBelle, PhD, Assistant Research Professor at Arizona State University, talks about new method researchers are studying to measure blood glucose levels.

We’re talking Diabetes…Why did you even get started in developing something for diabetes?

Dr. LaBelle: Because there was a need. My father actually had it before he died of lung cancer. He was developing type 2 diabetes, but there is a huge growing population of diabetic patients out there. Around 23– 25 million sufferers. And that number is going to triple by the year 2030. So, to me as an engineer it says people need help.

So, did your dad have to prick?

Dr. LaBelle: Yes. I asked him several times ‘How many times a day are you finger pricking?’ And he’d be ‘well, you know about 4 -6’. I’d ask my mom and she’d say ‘once’. I knew there was a lying issue at least in the family.

Did you ever ask him why he didn’t? What’d he say?

Dr. LaBelle: Oh, you know he’d forget. Sometimes he’d mention that it wasn’t the most pleasant thing to do. He was an old Navy guy so he was rough and grumbly, but he would always say he forgot. I could always tell he wasn’t really enjoying it.

So, did you go to straight to trying to test your tear?

Dr. LaBelle: We had some evolutions in our designs. We were hoping to try and make some sort of implantable device and it was pretty insurmountable for us, at least the way we were attempting it. So, we decided if we could take a tear fluid and start all over how would we get it? We did look at other body fluids, but tear fluid seemed to have a lot of literature about it. If we can take that sample off and put it on a sensor and record its levels of glucose maybe that would work. Later we integrated the sensor to go to the eye so we could bring it all to one device. I had a great student, Daniel Bishop’s, working on it. He’s an M.D.-Ph.D. now at University of Pittsburgh. Between the two of us we pretty much figured out the final device after about nine months.

I did a story at NASA once and they were getting these devices for the astronauts so they could test them up in space and they do a lot with the fluid in the eye. I think they said something like …everything in your body goes through your eye.

Dr. LaBelle: If you take aspirin it shows up in tear fluid. It’s really amazing. It’s another extension of the blood system, a lot cleaner. The biggest challenge, actually, is it’s a lot lower concentration. So, it’s a little bit easier to get samples from your eye, but it’s a lot harder to measure. That was, actually, where the literature led us too. We had a lot of design constraints we had to account for, low volumes, low concentrations and, of course, evaporation. That was one of the biggest challenges.

So, have you tested this on people yet?

Dr. LaBelle: No, no. We don’t have any approval for human testing yet. We’re planning to. That’s part of our goal…to do a quick turnaround. Test something basic touch the eyes, there is an irritation first and once we show efficacy in that we’ll move to “can we put the device in there and measure glucose there?”

How do you see it working?

Dr. LaBelle: Basically, if you poked your finger and you put the device next to your finger and drew the blood that way our device is that you don’t have to prick your finger or eye prick. You take the device and place to the white part of the eye, the conjunctiva, and just touch it. Basically, you can get a small volume, about 5 micrometers or less in a few seconds. That’s basically the device working. Then it would perform just like a regular glucose sensor. You’d plug it into the meter and take a reading.

How much is 5 microliters?

Dr. LaBelle: 5 microliters are about 1/200 of a little drop. If you’ve ever seen those commercials where people prick their fingers and there is just that little, little drop. That’s actually about 3 to 5 microlieters. It’s a very small little pinprick, not that large in volume.

Is it as accurate as the blood?

Dr. LaBelle: There’s a lot of literature that suggests that if you do it and capture the tear fluid without evaporation, without simulating the eyes, which is another issue, you can actually get just as accurate as blood glucose. There’s a little bit of a delay of maybe five to ten minutes between the blood glucose being digested and getting through the blood system to get to the tear fluid, but it shows up having a high correlation

What about cost?

Dr. LaBelle: Well, it’s an add-on device, so, in some regards you may say the sensor strip, the little screen print elector may be expensive because we are putting little manufactured pieces on it, but the cost overall may go down a little bit because now you don’t have to buy the lancets. In some ways I see it as it costing at least the same plus there is a patient population that is looking for more simplicity in the amount of paraphernalia they have to carry around with them every day. So, we removed at least the lancet.

When you say the ‘lancet’ is that the monitoring device?

Dr. LaBelle: The lancet is actually what you poke your finger with to draw the blood. The patients usually have to carry a supply of those around and maybe an insulin pen to give themselves insulin injections, the test strips, which is what we’re focusing on, and a glucose meter. They really have to carry all this paraphernalia with them. And it’s amazing how easy it is to forget one thing when you’re packing to go traveling. You forget your hairbrush, or your toothbrush, they forget their lancet. They can’t even take their measurements.

We’re, hopefully, making life a little bit simpler.

Can you show me how it works?

Dr. LaBelle: A lot of the times that we’re working we work with this type of scale because it’s easy to work with on the bench, but it wouldn’t be the thing we’d be touching to our eyes. So, the actual device itself is a micro-fluidic channel that would capture the tear fluid by touching it to the eye. It would then travel down this little channel here to the sensing region that would sit over the sensor and that’s where the electrochemical activity would be measured for the glucose. This is the bench top model that we would have and that you would basically see the polyurethane plug (that’s the part of the device that touches the eye) take the tear fluid from the eye then move it down to the sensing region as detected. These are basically the scale we use in the lab because it’s just easy to work on a nice flat surface. Eventually, what we want to have is something that works …this is basically, a regular self-monitoring glucose device with a modified device that we would make on it and you would touch it to the eye, take the sample and then put that into a meter and record. It would be the same as doing blood glucose.

Do you lose anything by doing it with the tear and not the blood?

Dr. LaBelle: Detection levels. Measuring things like blood glucose are a lot higher so the concentrations are 100 times higher than tear fluid.

What goes into the sensor?

Dr. LaBelle: well you have your standard electrochemical agents like enzymes and things like that. That’s still on the sensor but what gets to the sensor is everything that’s in the tear. Tear fluid contains many different things. There could be lipids. They’re little fat cells that come from our eyeball. If you scratch too hard you’ll actually pick some of those up and that’s a bad thing. That’s why we made our device to operate quickly. You’ll find things like acetaminophen or aspirin is sometimes found in tear fluid. Catecholamines, nor-epinephrine, epinephrine, dopamine are all found in tear fluid. Tear fluid is really complex, but what you won’t see is red blood cells, white blood cells and large interference like that. In some ways it’s a lot cleaner. It’s just that there is a lot less fluid to work with.

How long do you have to go until you can see this if it were touching the eye?

Dr. LaBelle: We actually shoot for less than five seconds. There’s a lot of literature that says that if you are on the eyeball longer than that there is a good chance that the person may move, scratch an eye or stimulate the eye. There’s nothing that would damage it because there are all soft components, but what could happen if we rub the eye the eye will actually give off a stress response and part of that stress response are elevated glucose levels. So, part of our design constraints was to get the sample and get off the eye. We haven’t optimized that yet, so, we’re hoping to take it faster than five seconds, but right now that’s about what we are using.

How long before you can see this actually being put to use?

Dr. LaBelle: There are all sorts of thing it will have to go through obviously with human subject studies. We have to show the direct correlation from fasting levels of glucose to elevated after a meal or something like that. We would then have to probably go through FDA approval. The nice part of this is we are not going into the skin, or through the skin, so we may get a five/ten K or something like that allowance. Hopefully under 3 -5 years. And that’s kind of why we went to this technology rather than trying to make it implantable. The development time there would be five to ten years.

But that could be the future? Implantable?

Dr. LaBelle: Definitely. There’s some wonderful work going on in that area.

Where would you implant this device?

Dr. LaBelle: Some groups are actually trying to do it on contact lenses. So, that’s one avenue. There was another push to try and go into the tear duct itself and measure the tear fluid as it’s coming out, but that’s a little bit more invasive. There are current devices on the market called punta plugs that they actually surgically implant into the tear duct to prevent over tearing and that requires a surgeon to implant those, so we wouldn’t want to do that.

Ok did I miss anything?

Dr. LaBelle: We have a lot of great students here. We do. A lot of the work has been supported of course by BioAccel most recently. They are a local non-profit organization that’s really given us tremendous support. We have wonderful clinicians, endocrinologists, and ophthalmologists at Mayo Clinic who have given their expertise. We may be bio-medical engineers, but we are not doctors, so we do have to rely on the experts. And, of course, I have a lab of wonderful students that range from bio-engineering, mechanical, chemical, and electrical and biology. About 34 students that are working on all sorts of really cool stuff.

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