Sympathetic autonomic neuropathy. If you're unable to sweat be lowyour waist, there is a possibUity that prolonged exercise maycause undue elevation of your body temperature.
Proteinuria. Elevated levels of urinary protein are usuaUy exacer bated by strenuous exercise. This in turn can accelerate the kidney damage that youmayalready have.
Ongoing Concerns for Exercising Diabetics FoUowing is a Ust of aspects of healthyou should consider on an on goingbasis as you pursueyour exercise program.
Recent surgery. A history of recent surgery usuaUy warrants re straint or abstinence until you receive clearance from your surgeon.
Blood sugar changes. Even after blood sugars are reasonablyweU controUed, illness, dehydration, and eventransient blood sugar values over 170 mg/dlare reasons for you to refrain from exercise. For many people, blood sugars above 170 mg/dl wiU increase further with exer cise, due to the production of stress hormones that we discussed pre viously.
Blood sugars below target values. Ifyoutakebloodsugar-lowering medications, do not exercise if blood sugar is below your target value. Bring it up to targetfirst withglucose (see the nextsection, and Chap ter 20, "How to Prevent and Correct LowBlood Sugars").
Possible foot injury.
If you've had diabetes for a number of years, thereisa goodchance thatyourfeet areespeciaUy susceptible to injury whUe exercising.
There are several reasons for this: • The circulation to your feet may be impaired.
With a poor blood supply, the skin is readUy damaged and heals poorly.
It also is more likely to be injured by freezing temperatures. • Injuryto nerves in the feet caused bychronicaUy highbloodsug ars leadsto sensoryneuropathy, or diminished abUity to perceive pain, pressure, heat,cold, and so on.
This enables blisters, abra sions, and the like to occur and continue without pain. • The skin of the feet can become dry and cracked from another form of neuropathy that prevents sweating.
Cracks in heels are potential sitesof ulcers.
Using Exercise to Enhance Insulin Sensitivity 219
• A third form of neuropathy, caUed motor neuropathy, leads to wasting of certain muscles in the feet.
The imbalance between stronger and weakermuscles leadsto a foot deformity very com mon among diabetics, which includes flexed or claw-shaped toes, high arches, and bumps on the sole of the foot due to prominence of the heads of the long metatarsal bones that lead to the toes.Theseprominent metatarsal headsare subject to high pressure during certain types of weight-bearing exercise.
This can lead to caUuses and even skin breakdown or ulcers.
The knuckles of the claw-shaped toes are subjectto pressurefrom the upper surface of your shoes or sneakers.
The overlying skin can therefore blister and ulcerate. • Another form of neuropathy makes it difficult to perceive joint positionin the feet.
This, in turn, canleadto orthopedicinjuries (e.g., bone fractures) whUe running,jogging, or jumping.
AU of this implies that the feet must be carefuUy protected during exercise.
Your physician or podiatrist shouldbe consulted before you start any new exercise, as some restrictions may be necessary.
Even prolonged swimming can cause maceration of the skin.
You should also be thoroughly trained in foot care.
Please seeAppendix D,"Foot Care for Diabetics." You or a famUy member should examine your feet daUy for any changes, abrasions, pressure points, pink spots, blisters,and so on.
Be sure to checkthe soles of your feet, usinga hand mirror if necessary.
If you find anychanges, seeyour physician immediately.
Bring with you aU the shoes and sneakers that you currently use, so that he can track down the cause of the problem.
Atthe very least he mayrecommend the use of flexible orthotic inserts and wide, deep toe box sneakers whUe exercising.
No attempt shouldever be madeby anyone (includ ing podiatrists) to remove calluses, as this is probably the most com mon cause of ulceration.
FOR DIABETICS WHO USE BLOOD SUGAR-LOWERING MEDICATIONS: COVERING EXERCISE WITH CARBOHYDRATE
People who do not take medications that lower blood sugar are usu aUy able to "turn off" their insulin secretion in response to a drop in
220 Treatment
blood sugar brought about by exercising.
You cannot, however, turn off sulfonylurea hypoglycemic agents or injected insulin once you've taken them. (This is one of the reasons I never prescribe sulfonylureas and simUar products.) To prevent the occurrence of dangerously low blood sugars, it is wise to coverthe exercise with glucose tablets (e.g., Dextrotabs; see page326) in advance of a drop in blood sugar.
Some type 1 diabetics try to use "treats," such as fruit or candy, to cover an anticipatedblood sugar drop.
I don't ordinarily recommend this approach, because it's not as precise as using glucose tablets.
My experience with patients who've taken raisins or grapes or candies to cover their exercise has been that they suffer subsequent elevated blood sugars.
Say you eat an apple.
It wiU contain some fast-acting sugars that enterthe bloodstream almostimmediately.
It wiU also con tain other, slower-acting sugars that may take several hours to have their fuU effect upon blood sugar.
On the other hand, as we wiU dis cussbelow,certain sustainedactivities , such as cross-country skung or physical labor for many hours , can keep your blood sugar drop ping aU day.
For those, you'll need something longer-acting to help keep you from becoming hypoglycemic.
To discover how much carbohydrate you shouldtake for a givenex ercise session requires some experimentation and the help of your blood sugar meter.
One valuable guideUne is that 1 gram of carbohy drate wUl raise blood sugar about 5 mg/dl for people with body weights in the range of 140 pounds.
A chUd weighing 70 pounds would experience double the increase, or 10 mg/dl per gram, and an adult weighing 280 pounds would probably experience only half this increase (2.5 mg/dl).
My own preference is Dextrotabs, each of which contains 1.6grams of glucose.
Other brands of glucose tablets are avaUable at most large pharmacies and diabetes maU-order suppUers (see Chapters 3 and 20).
If you weigh 150 pounds, one Dextrotab wiU raise your blood sugar about 8 mg/dl.
Sincethese glucose tablets start raising blood sugar in about 3 minutes and finish in about 40 minutes, they'reideal for rela tively brief exercise periods.
Let's run through a hypothetical example to demonstrate how you'd go about determining how many tabletsyou ought to take.
Let's assume you weigh 170 pounds and 1 Dextrotab wiU likely raise your blood sugarabout 7 mg/dl.You've decided to swim (or playtennis) for an hour.
Using Exercise to Enhance Insulin Sensitivity 221
• First, check yourbloodsugar before starting (you should always check blood sugar before starting to exercise).
If it's below your target value,take enough Dextrotabs to bring it up to target.
Wait 40 minutes for them to finish working.
If you don't come up to your target, you may be too weak to exercise effectively.
Record your blood sugar level upon starting. (I urge the use of Gluco graf data sheets for recording aU exercise-related blood sugars.) • When you begin such activity , the first time you exercise after beginning our regimen , take 1 Dextrotab, and then 1 again every 15 minutes thereafter. • Halfway into your activity, checkblood sugar again, just to make sure it's not too low.
If it is, take enough Dextrotabs to bring it backup, and continuethe exercise.
If it'stoo high,you may need to skip the next few tablets, depending upon how high the value. • Continue the exercise and the tablets (depending upon blood sugarlevels). • At the end ofthe exercise period, measure blood sugar again.
Cor rect it with glucose tablets if necessary.
Remember to write down aU blood sugarvaluesand the time when eachtablet was taken. • About an hour after finishing your workout, check blood sugar again.
This is necessary because it may continue to drop for at least 1 hour after finishing.
Bring it backup with glucose tablets if necessary. (Very intense or prolonged exercise maykeepblood sugars dropping for as long as 6 hours.) • If you required, say, a total of 8 tablets altogether, this suggests that in the future you should take 8 tablets spread out over the course of yourworkout.
If you only required 4 tablets, then you'd take 4 tablets the next time.
And so on.
For some exercise pro grams you may need no tablets. • Repeat this experiment on occasion, because youractivitylevel is rarely exactly the same for every exercise period.
If you required 3 tablets the first time and 5 tablets the second time, take the average, or 4 tablets, the next time.
If your activity level in creases , sayyou've been playing with a slowtennis partner and you find another who makes you sweat yourbutt off, you may find it necessary to increase the number of glucose tablets.
Thereare some activities where coverage with a slower-acting form of carbohydrate may be appropriate, and it's here, perhaps, that you
222 Treatment
could use the "treats" I would normally discourage.
For example, I have two patients, both on insulin, who are housepainters.
Neither works every day, and the hours of work vary from day to day.
They rarelywork for less than 4 hours at a time.The painter in Massachu setts finds that half a blueberry muffineveryhour keepshis blood sug ars level, whUe the painter in NewYork eats a chocolate chip cookie every hour.
Some patients find that their blood sugars drop when they spend a few hours in a shopping maU.
I teU them to eat a sUce of bread (12 grams carbohydrate) whentheyleave their car.
The bread wiU start to raise blood sugar in about 10 minutes, and wUl continue to do so for about 3 hours.
The cookies and blueberry muffinscontain mixtures of simpleand complex sugars, so theystart working rapidlybut alsocon tinue to raise blood sugar for about 3 hours.
I discourage the use of fruits, which can raise blood sugar less predictably.
If your exercise is not going to continue for many hours, coverit with glucose , not a fun food , if you want predictableresults.
Beware, however.
If you havea history of craving carbohydrate, fun foods are likely to exacerbate the problem, making the addiction im possibleto control.
Whatever your plan for coveringexercise with carbohydrate, always carry glucose tablets with you!
If you have gastroparesis, you may do better with a Uquidglucosesolution (see page 377).
WHAT FORM OF EXERCISE IS BEST FOR YOU?
As you are by now aware, insulin resistance, which is the hallmarkof type 2 diabetes, is enhanced in proportion to the ratio of abdominal fat to lean body mass.One of the best ways to improve this ratio in or der to loweryour insuUn resistance is to increase your lean body mass.
Therefore, for most type 2 diabetics, the most valuable type of exercise is muscle-buUding exercise. (It'sgood for type Is too, becauseit makes you feel better,look better, and can improve your self-image.) There also is cardiovascular exercise, which benefits the heart and circulatory system, and wiU be discussed later in the chapter.
First, what is muscle-buUding exercise?
Resistance training, weight training (weight lifting), or gymnastics would aU qualify.
If done properly, weight lifting has many attributes that make it superior to