Over time most of us experience a conditioning effect. This means that we tend to become more efficient at performing the same activity once we have had a chance to practice it. As a result, we burn less fuel and may require less of an insulin reduction. This also holds true for those who use food to prevent lows during exercise: Less food is required to maintain the blood sugar level as we become better conditioned.
Managing Pre-Activity Highs
Exercising with a high blood sugar level is rarely dangerous as long as there is at least a basal level of insulin in your body. Without a minimum level of insulin, exercise will cause the blood sugar to rise further and may accelerate the production of ketones, acidic by-products of fat metabolism. If ketones build up in large amounts and you become dehydrated, the delicate pH balance in the bloodstream and body tissues will become altered, and you will become susceptible to a lifethreatening condition called diabetic ketoacidosis (DKA).
Figure 7-7. Rating of perceived exertion chart
If your pre-exercise blood sugar is inexplicably high, there is one way to make sure you have sufficient insulin to allow for a safe exercise session: Check your urine (or your blood) for ketones. The presence of small, moderate, or large ketones in the urine, or a reading of greater than 0.5 mmol/l on a meter that measures ketones, indicates a lack of insulin in the body. Do not exercise if you have ketones; instead, drink plenty of water and contact your physician immediately.
If you do not have ketones, exercising should be safe as long as you address the high reading with insulin and drink plenty of water. However, high blood sugars during exercise can be a problem for anyone who wants to maximize their performance. As mentioned in Chapter 2, optimizing blood sugar levels during exercise can enhance your strength, speed, stamina, flexibility, and mental focus—all of which also add up to better athletic performance.
To treat high blood sugar prior to exercise, it is best to obtain a reading approximately thirty minutes before the activity. This will give the bolus insulin time to take effect before you start your activity. Because exercise has a tendency to amplify insulin’s effects, you may only need a bolus that is half of what you would normally give to cover a high reading. For instance, if your normal sensitivity factor is 40 points per unit (2.2 mmol/l), assume an 80-point (4.4) drop per unit if you are about to exercise. If possible, test your blood sugar during and after your workout to see how well this works, adjusting as needed the next time around.
For high blood sugar prior to exercise, take half the usual correction dose and drink plenty of water.
If you want to bring your blood sugar down as quickly as possible, consider giving the correction bolus by injection into a muscle rather than fat. An intramuscular injection can sting momentarily, but it will usually work twice as fast as an injection given into subcutaneous fat. Each unit given into muscle will have the same potency as a unit given into fat (i.e., lowers blood sugar the same amount), but it does so much faster.
Premeal Exercise
In some cases exercising before a meal will require a modest reduction in the bolus for the meal consumed after exercising. However, this is not usually necessary. If you notice that your blood sugar drops low after the meal following a workout, go ahead and reduce the bolus as needed.
In general, when exercise is going to be performed before or between meals, reducing the bolus at the previous meal would only drive the preworkout blood sugar very high. A better approach is to take the usual bolus at the previous meal and then snack prior to exercising. I will cover details regarding blood sugar management for premeal exercise in the next chapter, along with basal insulin adjustments for prolonged and exhaustive forms of exercise.
Inactivity: Sensitivity in Reverse
What goes up, must come down. Just as increased physical activity causes an improvement in insulin sensitivity, decreased activity can have the opposite effect. Anyone who has gone from a physical job to a sedentary one, or an active lifestyle to prolonged recuperation from an injury, knows what this is all about.
Any time you are very inactive at a time when you are normally active, your insulin is not going to work as well as usual. For example, this can happen when you spend several hours or more
•sitting in meetings;
•sitting in planes, trains, or automobiles;
•sitting at a show;
•working at a desk;
•working in front of the computer;
•napping;
•watching TV;
•playing video games; or
•reading.
Long periods of inactivity create a temporary state of insulin resistance so more insulin is required to get the same job done. When this happens, consider taking your bolus doses up in small increments—perhaps using a bolus multiplier of 1.1 (a 10 percent increase), 1.2 (20 percent increase) or 1.25 (25 percent increase).
For example, let’s say Armond is about to board a three-hour flight to Cleveland to visit the Rock and Roll Hall of Fame. Before giving his usual lunch bolus of 5 units, he multiplies the dose by 1.2 and gives 6 units instead. Rock on!
(Food Dose + Correction Dose – Insulin On-Board)
x Activity Adjustment
Part 5. Bolus Timing
Let’s see . . . so far, we’ve learned about key dimensions to figuring out a bolus: the part that covers food, the part that covers the blood sugar, and adjustments for insulin on-board and physical activity. These dimensions should just about do the job—unless you live in the real world, where the fourth dimension, time, is of the essence.
The timing of your boluses can make or break their effectiveness. To understand this concept, imagine yourself as a baseball player, batting against a very clever pitcher. Not only do you have to swing the bat at the level where the ball is, but you also have to swing it at the right time—when the ball is just crossing the plate. If you swing too early or too late, all you’ll hear is the sound of the ball hitting the catcher’s mitt and the umpire yelling, “STEEEERIKE!” Likewise, boluses must be timed properly. Even if the amount of the bolus is correct, giving it too early will cause a low blood sugar followed by high readings several hours later. Boluses given too late will produce significant hyperglycemia soon after eating. A properly timed bolus in the proper quantity . . . now, there’s a thing of beauty. (Excuse me . . . I’m getting all misty just thinking about it—sniff!)
The only assumption is that you will be using a rapid-acting analog (aspart, glulisine, or lispro) for your boluses. If you are still using regular insulin (or a premixed insulin that contains regular insulin), take all the advice given below and back it up twenty to thirty minutes.
In order to achieve optimal control of your blood sugar for the first couple hours after eating, the timing of your boluses should be based on a few key variables: the type of food you will be eating, your premeal blood sugar level, and the presence or absence of impaired digestion.
Glycemic Index
The glycemic index (GI) tells us how rapidly food raises the blood sugar level. Although virtually all carbohydrates convert into blood sugar eventually, some forms do so much faster than others. Pure glucose is given a GI score of 100; everything else is compared to the digestion/absorption rate of glucose. See Appendix C for GI listings for many common foods.
Most starchy foods have a relatively high GI; this means that they digest easily and convert into blood sugar quickly. Some starches, such as legumes (beans, nuts) and pasta digest quite slowly. Foods that have dextrose in them tend to have a very high GI. Table sugar (sucrose) has a moderate GI, whereas fructose (fruit sugar) and lactose (milk sugar) are somewhat slower at raising blood sugar. Foods that contain fiber or large amounts of fat tend to have lower GIs than comparable foods that do not. For example, French fries tend to raise the blood sugar more slowly than baked potatoes do, and apples tend to be a bit slower than apple juice. See Figure 7-8 for a summary of how glycemic index affects the timing and magnitude of the postmeal blood sugar ris
e.
Figure 7-8. Blood sugar rise based on glycemic index
Foods with a high GI (greater than 70) tend to raise blood sugar the fastest, with a significant peak occurring in about thirty to fortyfive minutes. Examples include bread, potatoes, cereal, white rice, and sugary candies. For these types of foods, you should bolus twenty to thirty minutes prior to eating. Doing so will allow the insulin peak to coincide as closely as possible with the blood sugar peak. And that, of course, will produce the best after-meal control. Bolusing for high-GI foods just before, during, or after eating is not ideal. The food will raise the blood sugar long before the insulin kicks in, thereby producing a significant after-meal blood sugar spike followed by a pronounced drop. If you are not sure how much you are going to eat, bolus for an amount that you are confident you will have and then give the rest when the meal is over. That way most of your bolus insulin will be on the job when you need it most.
Foods with a moderate GI (approximately 45–69) digest a bit slower, resulting in a more modest blood sugar peak approximately sixty to ninety minutes after eating. Examples include ice cream, orange juice, cake, and carrots. Bolusing thirty minutes before eating these types of foods could produce a low blood sugar soon after eating. You should bolus five to ten minutes prior to moderate GI foods.
Foods with a low GI (below 45) tend to produce a slow, gradual blood sugar rise. The blood sugar peak is usually modest and may take several hours to appear. Examples include whole-grain pasta, milk, yogurt, beans, and chocolate. The same slow, gradual blood sugar rise occurs when consuming meals or snacks over an extended period of time (such as holiday meals, popcorn, or party food) or having very large portions. In these situations bolusing prior to eating tends to produce a blood sugar drop followed by a marked rise a few hours later as the bolus wears off and food starts to take its effect. Instead, try these options when having slow-digesting foods:
•Bolus soon after eating. This usually gives the food enough of a head start before the insulin kicks in.
•Split the bolus into two parts: half given with the meal and the remainder given one to two hours later. Wearing a watch with an alarm can help remind you to give the second half of the bolus.
•Take regular insulin with the meal rather than a rapid-acting insulin analog. With its delayed peak and prolonged action, regular insulin does a better job of matching the blood sugar rise from low-GI foods.
•If you use an insulin pump, use a combination or dual-wave bolus, with 25 to 33 percent of the bolus delivered immediately with the meal and the remainder delivered gradually over two hours.
For a summary of bolus timing based on glycemic index, see Table 7-10.
Table 7-11. Optimal bolus timing based on glycemic index of food
High-GI food Bolus well before eating
Moderate-GI food Bolus soon before eating
Low-GI food, prolonged or very large meals Bolus after eating, or spread out delivery
Blood Sugar
The second major variable to consider when determining the optimal timing of your boluses is the premeal blood sugar level. To avoid an after-meal blood sugar spike or major drop, you should give the bolus earlier, when the blood sugar is elevated, and again later when the blood sugar is below your target range. Table 7-12 summarizes optimal bolus timing based on glycemic index and premeal blood sugar.
Table 7-12. Adjustments to bolus timing based on GI and premeal blood sugar
When Will It Digest?
What If I’m Still Spiking after Meals?
If you are timing your boluses properly but your after-meal blood sugar is still above acceptable levels, don’t give up. There are a number of very effective strategies that you can use to “Strike the Spike.” I will present these in detail in Chapter 9.
Put It All Together
(Food Dose + Correction Dose – Insulin On-Board)
x Activity Adjustment
TIMED PROPERLY
=
The Ultimate Bolus!!!
Congratulations!!!
Chapter Highlights___________________________________________
•Bolus doses should be based on four things: carbs, blood sugar, activity, and insulin on-board.
•Insulin-to-carb ratios allow you to adjust your dose to match your exact food intake.
•Correction doses are based on your precise target blood sugar and your sensitivity to each unit of insulin
•Deducting insulin on-board (insulin still working from recent boluses) from your boluses will help prevent hypoglycemia.
•Increased physical activity will usually require a percentage reduction in your usual bolus dose. Decreased activity may require a modest dosage increase.
•Frequent blood sugar testing/record keeping and using CGM can help you and your health care team fine-tune your bolus dosing.
•Proper timing of boluses is necessary to obtain the best aftermeal control.
CHAPTER
8
Welcome to the Real World
So there you are: Armed with a physiologically perfect basal insulin program and a set of bolus equations that would impress your old, crotchety high school algebra teacher, off you go to conquer your favorite Italian restaurant.
There’s going to be a half-hour wait for a table. “No problem,” you say to yourself. “My basal insulin should take care of that.” Well, thanks to a huge party that just won’t leave, that thirty-minute wait turns into sixty minutes. Irritated, you start walking past the table, clearing your throat as loudly as possible. No movement . . . time to hit the bar.
As time ticks away, the Diet Cokes turn into rum and Diet Cokes. Finally, the hostess calls out your name (mispronounced, but close enough). Elation quickly turns to frustration as she brings your party of four to a table for two. “I asked for a table for four,” you tell her.
“Are you sure? Well, I’ll have to see what we have available.” You can feel the veins in your head starting to swell.
Fifteen minutes later your group finds its way to a table for four. Your frustration grows once again as you check your blood sugar to find that it has risen a great deal since you left home. “I haven’t eaten a thing . . . how could this happen?” you ask yourself. Oh well, nothing a little extra insulin can’t fix.
Your meal features the usual array of breadsticks, salad with rich dressing, pasta with cream sauce, and cheesecake for dessert. Counting your carbs as carefully as possible, you bolus the exact amount your bolus formulas dictate. You even give the insulin after your meal because it contains a lot of slow-digesting foods—something you remembered reading about in Chapter 7. This is a plan that can’t possibly fail, right?
Wrong. On the way out of the restaurant, you start feeling a bit woozy. No problem—you whip out your trusty meter, smear on some blood, and it reads: “low.” Now you’re really confused. How could you possibly be low after a meal like that? No matter, grab a handful of mints from the hostess stand (it’s the least they could do after making you wait so long!) and let someone else drive home.
Hopefully, all is not lost. You did count your carbs and bolus the right amount, so your bedtime reading should be decent. In fact, it is only slightly above target, but given all you had to eat, that’s not so bad. A minor insulin touch-up, and it’s off to sleep.
That night, you have a nightmare about a giant lasagna chasing you with a fork. To make matters worse, you have to get up several times during the night to pee. Upon waking the next morning, you discover that your blood sugar isn’t just up—it’s way up. “That’s it,” you tell yourself. “I’m never going to that restaurant again. From now on, nothing but home cookin’.”
Welcome to the real world, where things hardly ever go as planned, and blood sugars don’t always turn out as expected.
In Chapter 3, we concentrated on the major factors that influence blood sugar levels: insulin and other diabetes medications, food (specifically carbohydrates), physical activity, and the liver’s secretion of glucose. W
e spent the next several chapters focusing on how to set up the insulin program and adjust doses to match those factors. Now it’s time to pay homage to the secondary factors: those pesky day-today oddities that tend to mess with good control.
The Other Stuff That Can Raise Blood Sugar
Anxiety/Stress
Anxious moments and nerve-racking situations happen to all of us. From speaking in public to test taking to a simple visit to the doctor or dentist—many events elicit a stress hormone response that causes, among other things, a sharp blood sugar rise. To the right in Figure 8-1 is a CGM readout showing a dramatic blood sugar rise I once experienced when I was late for an important meeting, hit a pothole and got a flat tire, and then discovered that the spare tire was also flat. Without the slightest bit of food, my blood sugar rose almost 300 mg/dl (17 mmol/l)!
Figure 8-1. CGM printout showing a stress response
Of course, different events cause different responses in different people. What causes a great deal of anxiety for you might have no effect on someone else. The key is to look for patterns. Is there something that causes a consistent blood sugar response in a given situation? It can be helpful to record the causes of your high blood sugars in your written records and then tally the causes to determine whether specific situations account for a large number of high readings. One of my clients did this and found that high blood sugars were occurring every time he watched a horror movie. Apparently, the stress hormone response to the sudden appearances of the knifewielding maniac was driving his blood sugar up.
Think Like a Pancreas Page 17