The Design of Everyday Diabetic Things

I figured I'd talk a little bit of the design of things used to treat insulin-dependent diabetes mellitus (IDDM). The equipment features interesting trade-offs between ease-of-use, safety, cost, effectiveness and comfort. There are two main sets of tools: one for checking glucose and one for injecting insulin.

The Glucose Meter

There are many different glucose meters, but I use a Bayer Contour, because that's what the doctors suggested. The meter requires a disposable strip every time I want to check my blood sugar. I insert the strip into the meter, and then hold a drop of blood to the test strip intake.


The gadget is the meter, the plastic container (above the gadget) holds the test strips, the lancer is used to prick fingers (I guess they didn't want to call it a finger pricker for whatever reaon), the mesh compartment holds microlets (finger prickers), and I have some alcohol swabs in the little compartment.


The meter with a test strip inserted. In order to get a reading I have to hold a drop of blood to the little chamber at the bottom of the strip.

What the meter looks like after a reading. I'm using mmol/L, not mg/dl, which is why the reading is so low. A person with blood glucose levels of 5 mg/dl would be in a coma.


The lancing device (finger pricker) with the cap off, along with an uncapped microlet and a capped microlet. You have to twist the cap off the microlet in order to use it; if a child swallows a capped microlet, the plastic is strong enough that the cap shouldn't come off. I think. I'm not really sure, and I'm not planning on running tests, but if you know a child who would be interested in swallowing one, please feel free to contact me.

The amount the microlet penetrates into your skin is adjustable via screwing the cap on the lancing device. Diabetics who prick their fingers a lot develop callouses, so depending on the thickness of the skin, the needle may need to penetrate farther.


I had initially thought the meter was really nice. They're really inexpensive, have some fancy features like alerts, and it is very easy to use. However, much like printers being cheap and ink being expensive, the meter is cheap but the microlets and test strips are very expensive. The microlets and strips cost about a dollar a piece, and IDDM people are supposed to check their blood sugar at least four times a day. You're also supposed to change the microlet (the needle used to prick your finger), as the microlet gets worn after use. In practice most type 1s I know only change the microlet once per day. Anyways, the $20 meter consumes over $1,000 of test strips per year (my insurance covers the use of about 1,600 test strips per year). Right now I'm checking my blood glucose levels about 7 or 8 times a day, since I'm still getting used to everything, but eventually it should go down to four or five times a day. If my insurance didn't cover the strips, I'd almost certainly use a meter with a strip disk, since they'd be cheaper long term.

Overall I'm pretty happy with the meter. It is a little bulky, so I'll probably pick up a smaller one that I could carry with me, but the fact that it was free and the strips are mostly covered by my insurance makes me happy.

Insulin pens

Once per morning and before every meal I have to give myself insulin. There are two types of insulin I use. Lantus, which acts very slowly over the course of about 20 to 24 hours, is called a basal insulin. I use Lantus once per day in the morning, though eventually I'll probably have to split it into a day and night dose. Apidra, which acts very quickly, is called a bolus insulin. I take Apidra before meals; the exact dose depends on the carbs in my meal, my current blood sugar, and the amount of sugar I expect to burn. The location of injection has an important role in how fast my body absorbs the insulin. Injecting in the thighs makes absorption quite slow, while the belly area absorbs quickly. I normally use my thighs for the slow-acting, and my belly for the fast acting. I have to rotate the exact site location, or else scar tissue builds up which can make absorption difficult.

The biggest danger with the pens is that I accidentally confuse the two types of insulin. While the pens are visually distinct, with different colors, I actually wish they were physically distinct --- in other words, the Lantus pen was larger than the Apidra pen. I'm not too worried about confusing the two, since I keep them in different spots, but it would be nice if they were more difficult to confuse.


I have my two pens with two sealed needles on the kitchen table. The pens are disposable; after the pen runs out of insulin, I throw them away. Before use, the pens have to be stored in a fridge. After use, the pens are good for 28 days. I write the date the pens expire after the first use, so I can easily track when I'm supposed to throw them away. The pens are small enough to fit in my pocket.


This is the dial on one of my pens. I choose the number of units to inject by rotating the dial.

This is where the needle screws onto the pen top, with the number of units of insulin units left in the pen displayed.

This is the needle after the seal is taken off. There are screw threads on the inside that screw onto the top of the pen. The needle is inside the plastic container, so it is quite difficult to prick your finger with this. If the needle falls, it won't jab anything.


The needle has two caps, an outer and an inner. The inner cap is color-coded to the size of the needle. Different injection sites require different needle sizes.

A 8mm and a 4mm needle attached to the pens. Before injection, two units are supposed to be "burned," or injected into garbage. Burning the units insures that no air is in the needle. My Apidra pen always has a small amount of pressure, which is why there is a drop of insulin on the end.

I think the pens have a phenomenal design. First of all, the screw cap allows the use of different needles. This is important because, as I previously mentioned, different sites require different needle sizes, and because the needle wears after use, a new needle is required every time. The screw cap doubles as a safety measure; you have to push and screw the needle at the same time to get the cap on, which kid-proofs the pen to a large extent. With a child, the real danger isn't that a kid plays with the needle; the real danger would be a kid injecting themselves with insulin. The screw dial also kid-proofs the pen to a certain extent. An additional feature is that as you inject, the screw dial resets to zero. This means that the default state of the pen is going to be to inject no insulin.

The injections are almost pain free. Insulin injections are subcutaneous, compared to vaccinations which can require injecting into a muscle. I barely notice them afterwards, which has contributed to how quickly I've gotten used to them. The needles and pens, while expensive, are also (almost completely) covered by my insurance.

As I stated earlier, the devices feature some interesting trade-offs. Overall, I've been very impressed by how little pain I've experienced. While I still wouldn't wish IDDM on anyone, it isn't as difficult to deal with as I had initially envisioned. However, my pancreas is still working at some fraction of capacity, so I'll have to wait and see if I think the devices are effective enough when my pancreas produces no insulin.