Biology 101

We are studying enzymes this week in high school biology. Labs? William is his own lab. He called to me while he was reading that the chapter dealt a great deal with enzymes used to detect glucose levels in blood and urine. In the book, they show how basic test strips can be used in testing.

So what about the CGM? Continuous glucose monitors also use enzymes, glucose oxidase. Our reading in Biology Matters, a text by Singapore Math, said that enzymes are catalysts to reactions, breaking down the substrate but leaving the original enzyme unchanged. So why, we wondered, does the CGM sensor wear out in a week or two? What is happening to those enzymes?

A little Googling, and I found the explanation on Diabetes Forecast:

All day, every day, the immune system is on the hunt for foreign agents in the body to destroy. Normally, that’s a good thing, as it wipes out viruses, unhealthy bacteria, and even cancer cells. But it’s bad news for a glucose sensor that the body sees as an invader. The super-secret ingredients in CGM sensors are the coatings that help persuade the immune system to leave the sensor alone. “The key to the intellectual property is tricking the body,” says Pacelli. “Ultimately, the body wins.”

So the enzymes are under attack by the body, ultimately getting through the coatings. If you want to understand more about how a CGM works, go to Diabetes Forecast. 

It is rewarding and amazing when what we are studying helps us to understand real world applications. Now on to more prep for Thanksgiving which will be a special kind of biology and diabetes lab. Loads of carbs and insulin to balance!

Arm-Chair Diabetes

He had balked at putting the Dexcom CGM on the back of his arm, but for $25, he is willing to try it. I winced as he pushed down the plunger. It is not a small needle that inserts the filament. Luckily, it needs only to be changed out every week or two. This placement is an experiment in an effort to get a little more sleep for me.

His favorite place to wear the transmitter is on his leg - more fat there, making insertion less painful. The location works well as long as he is awake. In sleep, he rolls over on it with all of his new grown up body. The blood in that area doesn't circulate and the sensor thinks the blood there has no glucose. It sends out an alarm to wake the dead, the dead being me. It doesn't seem to rouse him at all.

I had two choices: bribe him to try a new location or run his BG higher at night than I would like. He took the bribe.

I'd like to tell you that last night, I slept like a deaf dog (because in my experience, babies don't sleep) and we eliminated compression lows. We did eliminate compression lows, but sleep was elusive again. For some perverse reason, diabetes decided to actually make him go low at night, lasting until 4 a.m. I have written Basal Program 51 (meaning I've changed his basal rate at least 51 times in the past three years) to try to stop the nighttime lows.

The red dots show when he was low. Ideally, I'd like him to be between 90 and 100 all night.

The lack of data prior to 11 a.m. was during new sensor warm-up.

Daisy Head Maisy

To get in practice for taking a dog everywhere we go, I shook the car keys at Daisy, our 14 year old Beagle-dor. Her favorite thing, after eating anything except vegetables, is riding in the car. She went with me to pick up my groceries at Walmart's new pick-up service.

Driving through town, I opened the window. I watched her nose work the smells, vibrating almost, reading the air. She has an expert nose. In her day, I could say "find it" if I was missing a chicken, and she would track it down. More mentally Beagle than Labrador, however, she is more prey driven than people driven and not bonded to William but to me.

As the dominant animal in the house, Daisy tolerates no mischief. She quickly corrects any animals in our house misbehaving with a loud... well, I don't even know what to call it. Not a bark, not a growl. She yells at them. She hurts not a hair on their heads, but it startles the bejebbies out of them (and me). I am thinking she will be a good teacher for the new puppy.

I like to call her Daisy Head Maisy. from the Dr. Seuss book.

Layers (And I'm not talking chickens)

"LOW, LOW, LOW!" I pop from bed already walking towards my son's room on hearing the WAH-WAH-WAH alert and seeing LOW ↓↓ on his continuous glucose monitor (CGM). Two years ago perhaps, I would have been shaking. Now, experience under my belt, I walk calmly but with purpose. Sleeping the sleep of a teen, he's laying on the CGM attached to his leg. Though still growing,  he's man-sized. His weight compresses the area, slowing blood flow and any glucose in the blood, and making the sensor think he is low when he is not. He puts out his hand without waking. I test to make sure. 85 mg/dL.

While that is is perfectly good number during the day, and one I would like to maintain at night, I know from experience he will roll over again and again from side to side. Each time he lays on the sensor, it will wake me. Intellectually, I know he isn't low, but I can't take a chance by ignoring it and I will get up again.

I shoot for higher numbers at night, maybe 120 or 130, so that the sensor thinks he's only 75 when he lays on it, not setting off my low alert setting. I mutter to myself about urging him again to put the CGM on the back of his arm, but for now....I bring up his BG with a short reduction in insulin and go back to bed.

Before the low alarm last night, I got a different alarm: "NO DATA". I tested, and went back to bed. the alarm would go off every half hour. Somewhat confident that he was stable, I turned off the "no data" alarm, taking a chance to gain a bit of peace for the household. Sometimes, the CGM, confused by a compression or sudden drop or because the cat walked by (who knows?), will "lose" him. Either the sensor is trying to straighten itself out or the Bluetooth connection was lost.

This is one snapshot of one night in answer to the oft asked question: "Why an alert dog? Don't you have great technology?" Don't misunderstand: we have freaking awesome technology. And though the word is overused, I DO mean awesome and unbelievably magic compared to just a decade ago, heck compared to three years ago when we entered the game. But like all technology, it can fail and isn't perfect. Neither is a dog, who might sleep right through a low.

The dog will be another layer, another possibility of catching a problem. It's going to be time consuming, it's going to be hard, it's a very real risk of not working out. It's going to happen.

p.s. William's cat Luna, sometimes will watch me in the night check his BG. I've even seen her bite him when he was low to wake him. Like most cats, she does this when she feels like it, which isn't very often. So, she, in punishment for her lack of motivation, gets to share her boy with a dog.

Note: I am not a medical professional. Anything you read on this blog is not intended as medical advice. Please consult your own doctors if you have questions or concerns. 

The Beginning

Murphy will be ready to come home next month. We are as nervous as expectant parents. We should get a photo at 5 weeks, and she will be seven weeks when she enters our lives. It was suggested that I should chronicle our journey of training a diabetic alert dog from a puppy. Perhaps others can learn from what we do right, and what we do wrong.

From reading several books, we have at least successfully navigated the first decisions. That is, of course, if you ignore that we've completely set aside the dire warnings not to start with a puppy. Disaster and chaos lie ahead of us! Plowing ahead, we've chosen to find our puppy at a kennel  which breeds British Labs. (click here to see puppies from Wildrose) Highly recommended for their excellent nose, train ability, and fondness for their own human, the British Labs are somewhat smaller and stockier than their much larger American Lab cousins.

Murphy is a female, also advised in the books to avoid a "macho" male dog who might find it interesting to mark his territory. Not to disparage all male dogs, we are just trying to stack the odds in our favor. Her name derives from William's assertion that if something is going to go wrong, it will. Murphy's Law. Perhaps given his dual diagnoses, that can be understood.

I intend to also use this blog to share things I've learned of diabetes care. It may not interest those of you not touched by this dreadful disease, and you are welcome to page ahead to cute puppy photos. For now, a sweet, fat puppy snuggles for the night with her siblings, unaware that she has been chosen to be a hero.