Basal Insulin: What's the right amount?

The sad thing about doctors is that they aren't engineers, and this is doubly true for lawyers. So when you read about medications, everything's written by people who (a) don't think in terms of getting results out of feedback control systems, though that's what the body's all about, and (b) do think in terms of, "If I say something blatantly wrong, I'll get sued, but if I'm mealy-mouthed, I'm safe." This means that the dosage adjustment (titration) instructions for Karl's long-acting Lantus insulin are vague and simplistic, even by the standards of the intelligent layman: http://www.lantus.com/hcp/titration.aspx. Thanks, health-care industry!

So let's talk about feedback control systems, which is a fancy term for something that everyone already knows a lot about. If you set the cruise control on your car, the car will run at the speed you set, increasing the throttle when you're going uphill, decreasing it when you're going downhill, etc. Going up a really steep hill, you might not have enough horsepower to maintain your speed, so you slow down: "flat out" is all you've got. On a downslope, you might go faster than the speed you selected. So cruise control keeps everything constant under a certain range of conditions, but outside this range, you get what you get.

Karl's pancreas is still making some insulin. The pancreas has a very cool feedback control loop which, like cruise control, puts insulin into Karl's system at the right rate to keep his blood-sugar levels constant, within a certain range. The problem is that his pancreas can't make enough insulin to keep his blood sugar under control under most conditions. His pancreas' accelerator is pressed all the way to the floor and he's still not at cruising speed.

If we get his dosage right, injected insulin acts like a strong tailwind, allowing Karl to get up to speed without making his pancreas run flat-out. To continue the auto analogy, this reduces wear and allows it to cool off, so it will last longer.

Not only that, but by allowing the engine run most of the time at, say, 50% power instead of 100% power, if we get an unexpected hill, we can get over some hills without slowing down, because we have reserve capacity. Turning the analogy back to diabetes, if Karl eats a larger portion than we had calculated, so he receives less insulin than he should, or sneaks a snack without any insulin at all, his body has reserves that will cover it without spiking his blood sugar. Sweet!

Because Karl's pancreas is producing some insulin on its own, he can receive different doses of long-acting insulin and arrive at the same average blood-sugar levels. If he gets a low-ish does, his pancreas will provide more insulin, and if he gets a high-ish does, it will provide less. So within this range, the results will be equivalent -- except to his pancreas!

Since the goal is to keep his pancreas from being overloaded, we're aiming for a dose on the high side of this range. So far, we've determined that a dose of Lantus anywhere between 6 and 8 units per day gives about the same results, and we'll probably test 9 units soon. We're adjusting no more often than once a week, since day-to-day variations are wide enough to obscure the results.

Holding Steady

Eight months after being diagnosed with diabetes, Karl's holding steady, and, if anything, his blood glucose numbers are getting better.

We partly attribute this to our policy of adjusting his dose of long-acting Lantus insulin from time to time, with a rule of thumb, "If two doses give about the same results, give him the higher one, to take some of the load off his pancreas." The less hard his pancreas has to work, the longer it lasts (our goal is "forever"), and the more it can take up the slack if Karl has more cabs than expected. He was down as low as six units, we're at seven now, and we'll likely inch it back up to eight.

Because Karl's autism means that he likes his routine, he's settled into both a dietary and a daily medical routine very well. Because he doesn't pine for treats or change his mind about what he wants for dinner based on what's going on around him, it's very easy to stick with things that work. He's even very good-natured about going into Dairy Queen and getting one or two of their low-carb ice cream bars (the only things in the store that don't have inconceivable levels of sugar).

Everything would be golden if my employer, Citrix, hadn't shifted from an excellent Blue Cross health-insurance plan to a ghastly Cigna one. I'm thinking I'm going to have to buy supplemental insurance to maintain a decent level of care.

Here's Karl's blood sugar graph from the last month:

Karl at the Prom

Karl had a good time at the Special Ed Prom, though as usual he wore his headphones to cut down on the loud music. The local paper used a photo of Karl, so he's famous again.

On the diabetes front, he's relentlessly sticking to his routine and to his accustomed diet (peanut butter and honey sandwiches on reduced-calorie bread for every meal, and chicken nuggets for every meal but breakfast). We'd like him to have more variety! This keeps his carbs down, though.

He's starting to look forward to Atkins shakes as a snack, and since these have practically no carbs, they're something he can have without insulin. Most of the other no-carb foods (cheese, hot dogs, meat, etc.) he doesn't like until they're made into something like pizza, which sorta defeats the purpose!

Are You Positive It Isn't a False Positive?

We got a high blood-sugar reading the other night, a hundred points higher than we expected. "What happened? What did we do wrong? Did we forget to give him his insulin? Did he have a huge snack we didn't know about?" What we did wrong was forget that Karl was building a gingerbread house and hadn't washed his hands before doing his blood-sugar testing. D'oh!

He gets so little in the way of sugary foods that we don't always remember that "sugar on his fingers will mess up his blood-sugar tests."

Precision: Matching Carbs to Insulin

How can we get more precise control over blood sugar? We've been experimenting with a way that seems obvious but I haven't seen mentioned anywhere: Match the carbs precisely to the insulin dose.

For example, suppose Karl is going to sit down to a lunch of 51 carbs, for which, at 15 carbs per unit of insulin, he's supposed to get 3.4 units of insulin. Well, we can't give him 3.4 units. We can give him 3.0 or 3.5, but not 3.4. 

Because giving too much insulin is worse than giving too little (since giving too much leads to low blood sugar and the troubles that it causes, from hunger to fuzzy-mindedness to loss of consciousness), we round down, and Karl would get 3.0 units, which is four-tenths of a unit short of what he needs. We'd expect his blood sugar to end up about 40 points too high because of this.

On the other hand, if he had 52.5 grams of carbs, that would work out to exactly 3.5 units, so we could be right on the money. All we need to do is find 1.5 grams of carbs in a Karl-friendly package. What we use are Ritz Bitz, which come out to about 1.5 grams each. Problem solved!

So now he's getting anywhere between zero and four Ritz Bitz with every meal. It seems to make a real difference when his carbs are just short of the next insulin increment.

If you're using an insulin pen but aren't using one that allows half-unit dosage, you should be! The NovoPen Junior has been working very well for us. If we had to give insulin in one-unit increments, the number of Ritz Bitz we'd give Karl per meal would go as high as nine! He'd like that, but we wouldn't.

Adjusting the Carb Ratio

Looking at Karl's blood-glucose logs yesterday, we discovered that Karl hadn't had low blood sugar once in two weeks, but he'd had high blood-sugar many times. Since insulin is what brings his blood sugar down to normal, being never low but often high means, "too little insulin."

We use what's called "advanced carb counting," meaning that we figure out the grams of carbohydrates in every meal and divide this number by the "carb ratio" to get the number of units of insulin. 

I'm told that Type 1 diabetics whose bodies no longer produce any insulin have a carb ratio of around 8, meaning they get one unit of insulin for every 8 grams of carbohydrate. For Karl, we've been using a carb ratio of 16, meaning that he gets only half a much insulin as the diabetic with no insulin production of his own. This implies that Karl's pancreas is working at half efficiency.

Frequent high readings means that 16 is the wrong number, so we started using 15. The two numbers don't sound very different, but on a typical meal this happens to give Karl an extra half-unit of insulin. We've only been doing this for 24 hours, so the results aren't definitive, but it did exactly what we wanted: his post-meal ("post-prandial") blood sugar was in the 120 range, and his pre-mail blood sugar was in the 80-100 range -- both very good numbers!

It may also turn out that Karl's poor blood-sugar control with higher-carb meals was a simple "not enough insulin" problem.

One thing I've found frustrating in the literature is the weak, hand-waving descriptions of how to adjust insulin dosage. Come on, guys, this is the Age of Science! Is it possible that the problem is that, if you're clear, you might be sued, but if you're incoherent, you'll be left alone? Because basic information is so often mumbled when it needs to be shouted from the rooftops, and this means I haven't found any good "How to adjust your insulin dose" links for this post.

What we do is look at the trends for the last two weeks or more, especially comparing the frequency of lows compared to highs. Lows are scarier than highs, which is reflected in the normal guidelines, where it's considered okay to have several times more highs than lows. If that's not what we're seeing, then our dosage or our technique are not right. 

If your glucose meter comes with adequate software, as the Bayer Contour USB meter does, then you want the averages to be where they should be, the standard deviations to be as small as possible, and the highs and lows to be under control, biased towards modest highs rather than modest lows.

The standard deviation tells you how tight your control is but not whether it's centered around the right value. Getting tighter control, for us, happens when we:

• Reduce the number of carbs eaten
• Calculate the carbohydrates in each meal accurately
• Use the Novopen Junior for its half-unit dosing (insulin pens that only give insulin in one-unit increments are too imprecise)
• Don't cheat in any way.

Having mealtimes at the same time every day doesn't seem to matter for Karl, and if the portion sizes vary, this doesn't matter either if we've figured out the right carb ratio, so long as he doesn't go crazy on the carbs.

Random diabetes tip: The Swiss Miss sugar-free cocoa is sorta thin and unsatisfying, but adding a tablespoon or two of cream into the mix straightens that right up with only 1-2 grams of added carbs. (Avoid their "No Sugar Added" cocoa, since it's full of sugar.)

Leftover Insulin Drops on Injection

Last night at dinner, I noticed a drop of insulin still on the needle after his Novolog injection, and dampness around the injection site. We keep the needle in until a count of eight after the injection, which is supposed to prevent such things.

This time, though, it clearly wasn't effective, and Karl's blood sugar shot up to over 200, meaning that a whole unit had been lost, at least.

We're using the Novopen Junior insulin pen and BD 4mm nano needles and haven't seen this problem before. The instructions for the nano needles say, "Don't pinch the injection site," but Karl wants us to (it's how we were taught to give injections), so we still do. Arguing with an autistic kid is hard work, so we do things Karl's way when it seems okay to do so.

I wonder if the pinch is actually counter-productive with short needles? I wonder if there's a protocol for dealing with a seemingly messed-up injection like this? Estimating the loss seems like a difficult task.

A one-unit corrective dose got him headed in the right direction, though of course these never have the instant effect you'd like.