New Exercise Discoveries for Diabetes

You, of course, do both aerobic and resistance exercises.  Some people, however, skip the resistance exercises and others skip the aerobic exercises.  Is this wise?  And which should be done first?  Does it matter?

Two recent articles in Diabetes Care in April 2011 attempted to answer these questions.  The first study looked at the metabolic effects of performing one type of exercise before the other in patients with type 1 diabetes.  The scientists, from multiple centers in Canada, found that it does make a difference.   Subjects did 45 minutes of running before or after 45 minutes of weight lifting.  Those who did the weight lifting first were found to have much more stable blood glucose levels during and after the aerobic exercise.  They also have less frequent and less severe hypoglycemia after the exercise.

In a second study from Verona, Italy, patients with type 2 diabetes were put on a regimen of either aerobic exercise or weight training.  Both groups exercised 3 times per week for 60 minutes for 4 months.  Of course, the aerobic group ended up with more long-term stamina and the weight training group ended up stronger.  But the hemoglobin A1c was lowered the same in both groups, as were fat stores and insulin sensitivity.

Take Home Message: The effects of aerobic training and resistance training are different, are both highly beneficial, it’s better to do resistance training first, and my opinion is that doing both is at least twice as good as doing one or the other.

There are two old drugs that have been found to lower the blood glucose when they were used for other purposes. The following information describes their properties. Discuss them with your doctor if you need a bit more control of your blood glucose.

Bile acid sequestrants

Bile acid sequestrants are drugs that are used to reduce the total cholesterol and the LDL (bad) cholesterol. When they were being used for that purpose it was noted that they also lowered the blood glucose and the hemoglobin A1c. Although the lowering of hemoglobin A1c is modest, about 0.5 percent, these drugs may have a place in prediabetes or mild type 2 diabetes. They do not cause hypoglycemia.

The FDA has authorized the use of colesevalam (brand name Welchol) for this treatment. It can be used for both type 1 and type 2 diabetes. Side effects include constipation and nausea. Colesevelam comes as 625 mg tablets as well as 1875 and 3750 mg powder packets. The dose is 3750 mg once daily. It may be used alone or with other oral hypoglycemic agents and does not cause weight gain.

Bromocriptine

Bromocriptine is another drug long used for a different indication that has been found to have glucose-lowering effects. It has been used to treat brain tumors that produce too much growth hormone or prolactin. It was discovered to lower the blood glucose and the hemoglobin A1c to a slightly greater extent (hemoglobin A1c reduced 0.6-0.7 %) then the bile acid sequestrants but by a different mechanism. It also reduces triglycerides and free fatty acids, without causing hypoglycemia or weight gain.

Side effects include nausea, dizziness and headache in less than 15 percent of patients. The dose of Bromocriptine (called Cycloset) is 1 0.8 mg tablet increased by 1 tablet per week up to a maximum of 4.8 mg. It may be used by itself or with other oral agents.

Entrapment neuropathies are very common in people with diabetes, occurring in one in every three patients. These neuropathies result from squeezing of individual nerves as they pass through bony or ligamentous areas that do not allow expansion so the nerve is trapped if there is swelling for any reason. The entrapment neuropathies can produce symptoms similar to the mononeuropathies described in a previous post but they differ in several ways:

*  Onset of mononeuropathies is sudden while entrapment neuropathies have a gradual onset.

*  Mononeuropathies are self-limited, usually resolving over six weeks while entrapment neuropathies persist unless the nerve is released by surgery.

*  Mononeuropathies are painful from the start while entrapment neuropathies gradually get more and more painful.

The entrapment neuropathies include

*  Carpal tunnel syndrome: produces reduced sensation in the fingers and weakness touching the thumb to the fifth finger. The median nerve is trapped at the wrist.

*  Ulnar entrapment: produces reduced sensation in part of the fourth finger and the entire fifth finger as well as the hand between the fifth finger and the wrist. The ulnar nerve is trapped at the elbow.

*  Radial nerve entrapment: produces loss of sensation in the back of the hand and “wrist drop” from weakness of the muscles that straighten up the wrist. The radial nerve is trapped at the elbow.

*  Common peroneal entrapment: produces loss of sensation in the side of the leg and top of the foot and “drop foot” from weakness of the muscles that pull up the foot. The common peroneal nerve is trapped as it passes the head of the fibula, one of the two bones that begin at the knee joint and end at the ankle.

*  Tarsal tunnel syndrome: produces loss of sensation on both sides of the foot and wasting of the muscles of the foot resulting in decreased toe movement. It is like the carpal tunnel syndrome in the foot and results from trapping of the tibial nerve between two of the small foot bones.

*  Lateral femoral cutaneous nerve entrapment: produces loss of sensation on the outside of the thigh but no muscle weakness. It results from trapping of that nerve at the groin.

The entrapment neuropathies respond to rest, splints, drugs that promote water loss, injections of steroids and surgery if necessary. The important thing is not to confuse them with mononeuropathies

Neuropathy can affect the muscles that you move voluntarily and the muscles that move automatically like the heart, diaphragm and intestines.  The signs and symptoms will depend on which nerves are involved.

Disorders of Movement: Mononeuropathy

Mononeuropathy means loss of movement of the muscle activated by a single nerve.  The cause is believed to be the sudden closing of the blood vessel supply to that nerve.  If, for example, the nerve to one of the eye muscles is affected, the patient will be unable to turn his eye to the side that the muscle is on.  If it is the nerve to a muscle to the mouth, he may not be able to smile on that side of his face.  There can be trouble with vision or hearing on the affected side.  The patient may not be able to focus his eye.

There is no specific treatment for mononeuropathy, but it tends to improve and disappear after several months.

Disorders of Autonomic  (Automatic) Nerves

Your body contains an entire system of nerves devoted to movement of automatic muscles.  As you read this, your heart is automatically pumping your blood, your diaphragm is automatically pulling air into your lungs, your intestines are automatically pushing that large lunch you ate down from your mouth to your esophagus to your stomach to your small intestine and large intestine.  40 percent of people with diabetes have been found to have some form of autonomic neuropathy using sensitive tests.

Here are some of the different conditions that result from loss of autonomic nerves:

• Bladder abnormalities: the patient can’t tell when his bladder is full and he does not urinate regularly.  Urinary tract infections occur.  Treatment involves remembering to urinate every four hours and/or taking a drug that improves the force of contraction of the bladder muscles.
• Abnormalities of sexual function: in 50 percent of males and 30 percent of females.  The males have loss of erections and the females have loss of sensation and lubrication.
• Gastrointestinal abnormalities: The most common problem is constipation.  There is also delayed emptying of the stomach so that the food is not being absorbed while the insulin injection is active, resulting in brittle diabetes.
• Failure of the gall bladder to empty resulting in gall stone formation.
• Diabetic diarrhea and multiple (as many as 10) daily bowel movements.
• Heart rhythm abnormalities so that the heart fails to speed up with exercise or the heart rate may be very fast and fixed, not slowing with rest.
• Sweating problems, especially in the feet.  The body compensates from loss of sweating in the feet by sweating excessively in the face, arms and chest.

Key Advice

None of these disorders need ever occur if you keep your blood glucose in the normal range and maintain a hemoglobin A1c level of 7 percent or less.

There are many symptoms of diabetic neuropathy resulting from loss of sensation.  The following are the major types in the order of the frequency with which they occur.

Distal polyneuropathy

Distal polyneuropathy is the most common sensory neuropathy.  It involves the nerves of the feet and legs and often the hands as well.  It is believed to be caused by a metabolic abnormality, since other diseases that involve a metabolic abnormality can show evidence of a distal polyneuropathy as well (like kidney disease).

The primary signs and symptoms of distal polyneuropathy include the following:

• Numbness of the feet and legs and inability to know whether the feet are bent forward or back due to loss of large fibers
• Diminished ability to feel pain and heat or cold due to loss of small fibers
• Mild weakness
• Tingling and burning
• Painful sensitivity to light touch such as the bed covers on your legs
• Loss of balance and coordination
• Worsening of symptoms at night

A patient with this condition may not know if he has been burned by hot water, for example, or has stepped on a tack.  Most patients who have this condition do not realize it and need to have studies of nerve conduction in order to evaluate it.

Key Advice

Get yourself a 10 gram filament and test your sensation at least monthly.  If you can’t feel your feet, you must use your eyes to discover lesions.  To avoid distal polyneuropathy you must achieve very good control of your blood glucose so that you have a hemoglobin A1c of 7 percent or less.  Once neuropathy is present, examine your feet regularly.  If you have it, ask your doctor to check your feet at each visit.

Polyradiculopathy-diabetic amyotrophy

Polyradiculopathy-diabetic amyotrophy is a combination of pain on one side from the hip to the thigh and loss of motor nerve activity to the upper leg so that the patient can’t straighten the knee.  It does not respond to improved blood glucose control but usually has a short course.

Radiculopathy-nerve root involvement

Sometimes the pattern of pain suggests that the whole nerve is affected from its beginning at the spinal cord.  The pain is felt along a horizontal line from the spinal column to the front of the chest or abdomen.  This pain can be confused with an internal abdominal emergency.  But the pain goes away in 6 months to 2 years and it does improve with better glucose control.

Diabetic neuropathy is the damage to nerves that occurs after ten or more years of exposure to high blood glucose (sugar).    It affects 60 percent of people with diabetes who have the disease that long.  The actual signs and symptoms can vary from loss of sensation in the feet and legs to inability to move muscles that are controlled by specific motor nerves.   Still another type of neuropathy is called autonomic neuropathy and refers to loss of nerves that control the automatic functions of the body like the movement of heart muscle, the movement of the diaphragm to bring air into the lungs and the movement of food through the intestines.

Just why the nerves are damaged is not clear.  The explanation varies from loss of blood supply to the involved nerve or nerves to damage from toxins (poisons) that result from years of high blood glucose levels.  Diabetic neuropathy can lead to foot ulcerations, foot infections and amputations.  This is completely preventable.

There are several conditions that make neuropathy worse in addition to high blood glucose.  These include:

• Age: since neuropathy takes years, it is going to be worse in older people who have had the disease longer
• Height:   taller individuals have longer nerve fibers to damage
• Alcohol consumption: even small amounts of alcohol worsen diabetic neuropathy

Doctors check the various kinds of nerve fibers by testing with a tuning fork, hot and cold items and a filament that detects loss of light touch.  Here are the ways that this is done:

• Vibration testing, using a tuning fork, for example, can bring out abnormalities of long nerve fibers when the vibration is not felt.
• Temperature testing, using hot or cold items, tests for damage to small fibers, which are very important in diabetes.  When small fibers are damaged, the patient can lose his ability to realize that he is entering a burning hot bath.
• Light touch testing, perhaps the most important test that is done, detects the inability of large fibers to detect light touch.  The test is done with a thin filament.  The thickness of the filament determines how much force is necessary to bend it so that it is felt.  For example, a filament that bends with 1 gram of force can be felt by normal feet.  If a patient can feel a filament that bends with 10 grams of force, it is not likely that he will fail to feel an irritant that could damage the feet.  However, if a patient can’t feel a filament that requires 75 grams of force to bend, that patient is considered to have lost all sensation in that area.

The next articles will deal with specific syndromes in patients with diabetes due to loss of various nerves.

Prediabetes is defined by your blood glucose (sugar) just like diabetes. Here is a table that shows you normal values, prediabetes values and diabetes values for the blood glucose.

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Diabetes mellitus that develops during a pregnancy is called gestational diabetes. It occurs in about 2 percent of pregnancies. During pregnancy, the growing fetus and the placenta (the tissue between the mother and her baby) create various hormones that help the fetus to grow and develop properly. Some of these hormones have other characteristics, such as anti-insulin properties that decrease your body’s sensitivity to insulin, the hormone that controls the blood glucose, causing glucose to rise. Other actions of the hormones include increasing glucose production, with a further rise in the glucose.

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