Sunday, January 5, 2014

Adjusting Insulin Dosage

A lot of diabetics leave insulin dosage to their doctors, and don't see their doctors very often. Others adjust their dosage themselves, cutting out the middleman.

Most drugs on the market, including the insulin Karl uses, have "patient information" and "physician information." We always read both.

As an engineer, I've been amazed by the primitive nature of the dose-adjustment information given to doctors. I realize that doctors are not as well-trained in basic numerical methods as engineers, but still...

By the way, one of the larger barriers to doing a good job has been whittled away recently. The newer Bayer Contour blood glucose meters, the Contour Next series, lets you enter the number of carbs and the insulin dose on the meter, which now has the full set of information (time, blood glucose, carbs, insulin) to let you analyze the results without typing pages of information from a hand-written log.

Anyway, like most Type 1 diabetics, Karl is on a long-acting insulin (Lantus) and a mealtime insulin (Novolog).

The numerical analysis challenge goes like this:

  • You want to give mealtime (bolus) insulin that's just right to handle the carbohydrates in the meal. This uses a carb factor, the number of grams of carbohydrate per unit of insulin. Get this right, and after the meal, blood sugar will be the same as before.
  • In addition, if blood sugar levels weren't perfect just prior to the meal, you want to adjust the insulin up or down to correct for this. This is the correction factor, the number of points the blood glucose value changes per unit of insulin, in the absence of food.
  • For long-acting (basal) insulin, you want a value that, in the absence of food, keeps the blood glucose levels steady all day.
Fair enough, but all three effects are going on all the time, so getting them all right is a bit of a trick.

I have not yet seen any publication where anyone even tries to do the number-crunching properly, or even to give useful rules of thumb, except for the long-acting insulin, where the rules are variants of, "Pay attention only to fasting (pre-breakfast) glucose levels, and adjust the dose of basal insulin, perhaps by one unit a day, until it yields numbers close to, but slightly less than 100, on average." 

Sure, they have rules of thumb for starting new patients on insulin, but that's about it.

Karl needed an increase in insulin dosages recently, as his numbers were creeping upwards, and what I did was as follows:

  • Adjusted the long-acting Lantus dosage upwards to get his morning numbers below 100, knowing that some of the problem was really that he also needed more mealtime insulin, and that I'd likely end up adjusting them downwards in the end, at least a little.
  • Looked at meals where Karl's pre-meal blood glucose levels were okay, so there was no correction, and thus the correction factor was not part of the picture. The difference between before-meal and after-meal blood glucose revealed the degree by which the carb factor needed adjustment. It turned out that he needed 9 carbs per unit instead of the previous 10.
  • Looked at meals where Karl's pre-meal blood glucose was high, requiring a significant correction, and what the post-meal blood glucose was. This gives a hint at what the correction factor should be. This required a significant correction, from 85 points per unit to 45 points per unit. I also double-checked this with a rule-of-thumb table about what the corrective dose is likely to be, based on daily insulin consumption, though of course I value actual results with Karl specifically to anyone's table about patient populations in general. Note that if the carb factor and correction factor are both out of whack, it's hard to adjust them both at the same time with any precision, but you can do them sequentially.
  • As predicted, the adjustments all called for an increase in insulin (not a surprise, since his blood glucose numbers had drifted upwards), and once the other two numbers were adjusted, the long-acting Lantus dosage proved a bit high, and we backed it off by one unit per day so far, and may back it off by one more.
This seemed to work pretty well. I probably ought to do regression analysis for more precision, and after we've switched over to the new Bayer Contour Next meters, I'm likely to take a stab at it.

The Bayer Glucofacts software that comes with the meter is pretty primitive, as I've said, but the better the control, the lower the standard deviation between readings, and the closer the average reading is to the target value. 

Wednesday, October 2, 2013

Test Results

Karl developed an aversion to blood work, but on the second try and quite a bit of help from the folks at Philomath Family Medicine, we got it done.

The trick was to get a prescription for Lidocaine ointment and apply this topical anesthetic an hour before the appointment, telling Karl that this would help a lot, and doing the blood draw in a different room from usual. This process was more to his liking, which is just as well, because it took the nurse quite some time to find the vein!

Blood Sugar Well-Controlled

Two years after being diagnosed with Type 1 diabetes, his average blood sugar level, as measured by the Hemoglobin A1c test, is at 5.3% -- within the normal range! Yay, Karl! This presumably means that he is no more likely to have diabetes-related health complications than a non-diabetic. Whew!

How do we do this? Karl's rigid dietary preferences help, because we know how many grams of carbs are present in everything he eats. And the sensible use of intensive insulin therapy, with long-lasting basal insulin and fast-acting mealtime insulin, is essential.

Adjusting insulin dosage. One thing we do that many people don't do is to adjust Karl's dosage based on experience. We don't wait for a doctor's okay -- or even ask, for that matter.  Some people wait until the next time they see their doctor to adjust anything, even if their next appointment isn't for a year and their numbers are way out of line! That's a bad idea.

For his basal insulin -- we use Lantus -- you can find the "titration" recommendation online. Basically, we look at the morning blood-sugar levels and adjust the dose until they're in the right range. This can be repeated if they wander out of the range again (looking at a few weeks as an average). Karl started out with about 7 units of Lantus a day and is getting 18 now. We split this into a morning injection and an evening injection.

Similarly, for mealtime (bolus) insulin, if the blood sugar numbers are consistently high or low after meals, we're clearly giving the wrong amounts of insulin. Over the past two years, the right amount has drifted from 20 grams of carb per unit of insulin to 10.

Being willing to adjust the dosage according to the data is probably a big reason why Karl's A1c numbers are so good.

Pancreas Hanging in There

Another important test, C-Peptide, measures how much insulin Karl's pancreas is still making. The "acceptable" range is 0.9-6.9 ng/ml, and Karl came in at 0.7. It was actually in the "acceptable" range last time we tested it, two years ago, which shows how blood tests don't tell the whole story, since being hospitalized with extreme levels of blood sugar isn't what I'd call acceptable!

People will tell you that Type 1 diabetics don't have any pancreatic function at all, and their C-Peptide tests will come in at zer0. That's nonsense. Pancreatic function in Type 1 diabetics is impaired, and typically declines, often to zero -- but writing the pancreas off is pessimistic and stupid.

To help preserve the pancreas, we do a few simple things:
  • Maintain excellent blood-sugar control. This puts less of a load on the pancreas, which isn't literally killing itself by producing all the insulin it possibly can, 24/7, because the injected insulin is removing much of that load.
  • Supplement with niacinamide and vitamin E. A few studies show benefit from this.
  • Maintain a low-ish carb diet. The more carbs you eat, the poorer you blood-sugar control and the more your blood sugar spikes. Carbs reach the bloodstream faster than injected insulin, but the fewer carbs you eat, the smaller the spike And an error of, say, 20% in estimating the carbs in a meal makes only half as much difference if you're eating only half as many carbs. Karl eats only about half as many carbs as are recommended for a typical diet.

Wednesday, June 5, 2013

Two Years of Type 1 Diabetes

Next month will be the second anniversary of Karl's illness, hospitalization, and diagnosis of Type 1 diabetes, and it's so far, so good. 
His insulin usage has gradually increased, and is now at 17 units of Lantus per day for a basal dose, plus one unit of Novolog for every ten grams of carbohydrates in his meals. I rough figures, this is about twice his original dose, meaning that his pancreas has been gradually producing less and less insulin.
We were told to expect a "honeymoon period" of relatively low insulin requirements and stable insulin requirements that ended suddenly, but this didn't happen. 

Possibly this is because we deliberately decided to see what we could do to to stretch things out. Among these things were:
  • Use of a relatively low-carb diet (averaging around 60 grams of carbs per meal, which requires less insulin and thus allows better control of blood sugar.
  • Use of the Novopen Junior insulin pen, which officially allows insulin to be delivered with a half-unit resolution, but which probably allows precision to one-quarter unit or better. (For example, if we want to give 5.25 units, we dial in 5.5 units, then back off to halfway between the 5.5 mark and the 5.0 mark.)
  • Karl likes the same meals over and over, so we get really good at comparing the before-and-after blood sugar levels to find the right level of insulin.
  • Giving Lantus morning and night, rather than at bedtime only, because its response curve doesn't stay flat for a full 24 hours for everybody.
  • Use supplements: Insulow and evening primrose oil at every meal and daily supplements of mutlivitamin, vitamin B3, and vitamin E.
  • Refusing to freak out.
Karl's very fussy about maintaining his insulin kit just so, and that means we're almost never caught short when we go out to eat.
On the downside, Karl has refused to let the nurse take blood samples the last couple of times, so we haven't done detailed bloodwork recently. And his blood glucose regulation is getting less good as his insulin requirements increase, since the pancreas is far better at this kind of thing than any kind of insulin therapy, however spiffy and modern, so the less his pancreas contributes, the wider the blood-sugar swings, though we're still doing pretty well.
What's next? Perhaps reducing Karl's carbohydrate intake some more. The fewer carbs he eats, the less need for insulin, the lower the load on his pancreas, and the narrower his blood-sugar swings will be. We've done pretty well at keeping a typical meal at 60 grams of carbs, but Dr. Bernstein's regimen recommends no more than eight grams of carbs per meal, and that would be a huge change! 
So far, Karl has had no hypoglycemic episodes and no infections, and we'd like to keep it that way.

Tuesday, June 19, 2012

Illness and Diabetes

Karl's recovering from a cold, his first real cold since being hospitalized over a year ago. Man, oh man, did his blood-sugar levels go up! Bedtime readings were above 200 three days in a row.

Illness tends to raise blood-sugar levels in diabetics, and if there's dehydration involved, it gets much worse. Karl doesn't like our tap water, so we made sure the supply of bottled water and sugar-free drinks was unusually ample, using the lure of yumminess to overcome any reluctance brought on by lethargy.

Corrective doses at mealtimes were clearly not enough to bring his blood sugar back to normal, so we started a two-pronged strategy of increasing his long-acting Lantus dosage from 8 units a day to 10, and also added an extra 0.5 units per meal in addition to the calculated value. Both corrections together have gotten him into much better territory.

As things normalize, we'll first abandon the extra 0.5 units per meal and then back the Lantus off to suit. If Karl were to suddenly snap back to normal without warning, we might have to give a couple of small snacks to keep his blood sugar up, but it seems far likelier to me that he'll drift rather than snap back to normal.

I have not reviewed all my diabetes books for corroboration, since it's not rocket science to conclude that "if blood sugars are way too high, give more insulin."

We are also giving plenty of Insulow (alpha lipoic acid), which in some ways mimics the effects of insulin and also tends to reverse some of the damage of high blood sugars. While I suppose it's possible to overdo this, since alpha lipoic acid will lower blood sugars, and this could cause trouble if you're not paying attention, we've never seen any evidence of this. Karl normally gets 200 mg per meal, for 600 mg per day, but in his case giving twice this much has little effect on blood sugars. Apparently it's different for some people.

Karl didn't ask for cold medication. Dr. Bernstein's book paints a scary picture of aspirin, ibuprofen, and similar drugs, which can apparently  crater blood sugars unpredictably, and Tylenol, which is hard on the liver if you're dehydrated. Karl's pretty content with sugar-free cough drops as the only treatment.

Thursday, May 3, 2012

Dairy Queen for Low-Carb Meals?

Normally, you'd expect a place with as heavy an emphasis on sugar as Dairy Queen to be a non-starter for people like Karl who need to watch their carbohydrates, but they have three different low-carb ice cream bars: my favorite, the vanilla orange bar, with 12 grams of carbs, the fudge bar, with 7 grams, and the no-sugar-added Dilly bar, with 19. So if you're on a low-carb diet, you can have dessert at DQ.

And, oddly enough, they have a very good (and large) grilled chicken salad that's very low in carbs, too.

Not to mention the usual fast-food expedient of bunless burgers, which have very low carbs indeed.

Karl's unwavering preference is for chicken strips, which are higher-carb than the above-mentioned alternatives, and he has a weakness for french fries. Sigh. What this means is that I'm eating a lower-carb diet than he is, though he's diabetic and I'm just losing weight. 

But for most meals he eats fewer than 60 grams of carbs, and in our experience it's looks like Dr. Bernstein was right, and eating fewer carbs not only means a Type 1 diabetic needs less insulin, but the blood-sugar levels are more stable. 

And Karl has gone from being painfully thin at the time of his illness to putting on weight steadily, so it looks like low-ish carb diets have real promise for weight stabilization. They're not just for weight loss.

See you at DQ!

Monday, April 2, 2012

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: 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.

Sunday, March 25, 2012

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: