Exercise and Diabetes Mellitus

In textbook terms, Diabetes Mellitus (DM) is defined as a chronic disorder that’s characterized by increased blood Glucose levels (or hyperglycemia, in medical terms) and impaired processing of other key nutrients such as fats and proteins. (stats) The disorder is caused by under-production or inefficiency of Insulin; a hormone that plays a key role in the regulation of blood Glucose levels.

The role of Insulin in the regulation of blood glucose

A quick look at how Insulin works in maintaining normal concentration of Glucose in the blood should help us have a good understanding on how Diabetes works. This also goes a long way in understanding related treatment methods, and how exercise has a positive influence on the treatment outcomes.

Insulin is produced by the Pancreas, and it performs 2 major functions:

- Facilitating the absorption of Glucose by body cells.

- Facilitating the formation of fats, Proteins and Glycogen.

When the production and action of Insulin is compromised, the body’s capacity to use Glucose as a source of energy, as well as its ability to break down Proteins and fats becomes impaired. This ultimately leads to a number of problems, which we’ll consider shortly under the complications section.

To maintain balance, a number of hormones limit the effects/action of Insulin. A hormone known as Glucagon furnishes a good example. Its role is mainly seen in the Liver, where it facilitates the conversion of Glycogen to Glucose. Additionally, it’s also instrumental in the formation of Glucose from other nutrients such as Proteins and Fats.

When you are involved in exercise, the body adjusts to the physical demands by limiting the production of Insulin, while enhancing the production of Glucagon and other anti-Insulin hormones. This allows the blood Glucose levels to stay constant regardless of the increased physical activity levels.

However, the body still needs Insulin to absorb and use the available Glucose. Therefore, it triggers a compensatory mechanism, which results in increased sensitivity of body tissues to Insulin. This allows the body to use diminished Insulin reserves efficiently enough to maintain balance.

Types of Diabetes Mellitus

There are two types of Diabetes Mellitus based on the primary cause: Insulin-Dependent Diabetes Mellitus (IDDM), and Non-Insulin Dependent Mellitus (NIDDM).

Insulin-dependent Diabetes Mellitus (Type 1 Diabetes Mellitus)

This type of Diabetes is caused by a significant reduction or complete lack of Insulin. Its manifestation typically begins in early adulthood, and may be the result of various factors. It is commonly caused by a phenomenon known as autoimmunity, where the body’s immunity mistakenly identifies Insulin-producing cells as foreign. This consequently triggers a series of reactions which result in the destruction of these cells.

The development of this abnormal response against Insulin-producing cells has been linked to infection of certain Viruses i.e Polioviruses and Cocksackie virus. However, the mechanism is still a matter of speculation in the scientific community. The disorder has also been linked to heredity, in the sense that siblings of those who are affected are ten times more susceptible. Type 1 DM can also be a result of other conditions which can directly/indirectly affect the Pancreas such as Tumors and Cushing’s Syndrome.

Non-Insulin Dependent Diabetes Mellitus (Type 2)

This is by far the commonest form of Diabetes, accounting for almost 70-90% of affected individuals. Unlike Type 1 DM, it usually starts manifesting later in life, typically in the early 40’s. It is caused by enhanced resistance to Insulin, especially in the body’s peripheral tissues such as Muscles.

Causes

A number of factors come into play when it comes to the development of the disorder. Overweight/Obesity seems to be one of the key factors. Statistics have shown that about 80% of individuals with this disorder are Obese, whereas the other 20% is above what’s typically considered as appropriate weight.

In this population, Hyperglycemia (high blood Glucose) is a typical problem due to a mismatch between Insulin demand and production. In most cases, the Pancreas is unable to produce enough Insulin to cater for the growing demand. Additionally, body cells lose the ability to bind to Insulin, which compromises the effects of Insulin on those cells.

Age also plays a role in the development of the disease in the sense that the pancreas’ ability to produce Insulin becomes relatively compromised. This tends to interact with other factors to initiate the development of the disease.

Sustained psychological or emotional stress has also been linked to the disorder. Stress increases the concentration of a number of hormones including Glucagon and Norepinephrine. These hormones cause the blood Glucose to rise, which means increased demand for Insulin. This in turn burdens the Pancreas.

Medications and contraceptives can also be culprits in the development of the disease. Good examples include Thiazide Diuretics, which were demonstrated by Norris in the early 90’s to have a counter effect to the action of Insulin.

Complications of Diabetes Mellitus

Diabetes can have a number of life threatening and disabling complications which necessitate sound management. These include:

- Stroke.

- Heart Disease.

- High blood Pressure.

- Kidney Disease.

- Blindness.

- Nervous system abnormalities.

- Blood vessel problems which may lead to amputations.

Treatment

Normalizing Glucose levels is the primary goal of Diabetes management. This helps to prevent, and possibly reverse some of the complications associated with the disease.

Although there are standard guidelines, the choice of the methods depends on individual factors, which may differ from person to person. The overall treatment plan should be done holistically, and it usually includes patient education, medication, and exercise. Surgical interventions such as Pancreas transplantations are also available. However, these are still under investigation as a possible solution for Insulin-Dependent Diabetes Mellitus.

When it comes to Type 1 DM, Insulin Therapy is a necessity. Insulin Therapy involves infusion of preparations of Insulin in the blood as an attempt to maintain normal Insulin levels. After a thorough assessment, a medical practitioner may prescribe daily injections of specific Insulin preparations. In cases where intensive therapy is needed, the Doctor may use appropriate methods such as Continuous Insulin Subcutaneous Infusion (CSII), which uses a specialized Insulin pump aimed at maintaining normal levels. This has opened up possibilities for Diabetics, especially when it comes to participation in elite sports where affected athletes can compete in a safe manner.

Exercise and Diabetes Mellitus: Is it worth it?

Currently, there has been considerable research efforts aimed at evaluating the effect of exercise in both types of Diabetes. The early 80’s saw prominent researchers such as Trovarts and Cartas come up with groundbreaking studies which were focused on investigating the facts in this area. Since then, the results have been encouraging so far as there is remarkable evidence suggesting that carefully planned exercise has the capacity to improve insulin sensitivity and positively impact on the levels of Lipids and Proteins in the blood.

However, the findings haven’t been as favorable for Type 1 DM patients in terms of blood Glucose levels control. For instance, extensive studies done by Henrik and Gunnarson in the late 90’s were not able to demonstrate any significant changes in terms of blood Glucose control. Since then, no other studies have come up with conflicting results.

Though this is the case, exercise remains valuable in patients with Type 1 DM as it positively affects other important factors such as physical capacity and body fat composition. This is important when it comes to reducing the risk of associated complications while improving overall well-being.

Exercise Guidelines for Type 2 Diabetics

- Blood Glucose levels within the 100-250mg/dl are considered safe. However the overall goal of exercise should be to achieve more effective control. A common goal for younger persons is to deliver blood Glucose levels within the 80-120mg/dl range. For adults, the upper limit can be extended to around 180mg/dl. However, it is also important to remember that measurements over 120mg/dl should be closely monitored.

- Carbohydrate snacks are a necessity when it comes to ensuring that appropriate blood Glucose levels during exercise. The snack should be taken especially in cases where the pre-exercise blood Glucose level falls anywhere below 70mg/dl.

- Both the Diabetic and anyone who is monitoring the exercise session should be aware of the potential signs and symptoms of related complications. Key complications include Hypoglycemia and Diabetic Acidosis. Major signs include weakness, Acetone breath, nervousness, dehydration, tremors, altered vision, and confusion.

- In cases of Hyperglycemia, honey or fruit juice can be helpful.

- Careful planning is a cornerstone of success. Key factors include food intake timing, amount, and Insulin administration.

- Avoid engaging the exercise routine at peak insulin times. Peak insulin activity occurs at varying times and durations based on a number of factors including dosage, type and timing.

- Do not exercise during night hours. Hypoglycemia tends to kick in during sleep hours after heavy exercises done during late hours.

Now let’s take a look at the specifics relating to different phases of the exercise session.

Key things to consider before exercise

- Glucose levels should be accurately established. Avoid exercise when glucose levels are around 250mg/dl.

- Exercise should be carried out 1-2hrs after a meal. 1 hour is considered ideal.

- If you are on a daily dosage of short-acting Insulin, avoid injections in sites that will be primarily involved in the exercise at 1 hour before the exercise. The reason is that Insulin gets absorbed more rapidly in these sites.

- In cases of Insulin Dependent DM, either the dosage has to be decreased, or the food intake increased.

- Avoid substances that facilitate exercise-related Hypoglycemia. These include alcohol and other medications such as Phenytoin, Estrogen and Beta Blockers.

- Menstruating women may need to increase Insulin dosage. This especially applies those who do not exercise regularly.

During exercise

- Exercise for at least 5 times per week. Ideally at the same time.

- Ensure 40-60 minutes per session is achieved, although 20-10 minutes is beneficial. Track your Heart Rate as well to ensure adequate levels of exercise intensity.

- A target Heart Rate of 40-60% of the Maximum Heart Rate is a good starting point. Having an exercise professional for assistance is of paramount importance in this case.

- Carbohydrate snacks should be taken systematically. Ideally, snacks which can be rapidly absorbed such as fruits should be taken after the first 30 minutes. After the session, it’s advisable to consume carbohydrates which are absorbed at a slower rate. Good examples include bread and pasta.

- Exercise should be halted upon any signs of Hypoglycemia.

- Always check blood Glucose after 35 minutes of continuous exercise.

- Be sure to replace fluid losses. Due to the possibility of complications, individuals should always be monitored by relevant health professionals with sound knowledge of management i.e Physiotherapists and Doctors.

After exercise

- Glucose levels should be checked at 15 minutes after exercise.

- Increase the intake of calories over the next 24 hour period. This depends on the intensity and overall duration of the exercise.

- Reduce the dosage of Insulin based on the intensity of the exercise.