Diabetes Mellitus

| What is diabetes mellitus? | What is the impact of diabetes? | What causes diabetes mellitus? | What are the different types of diabetes mellitus? | What are the symptoms of diabetes mellitus? | How is diabetes mellitus diagnosed? | What is the oral glucose tolerance test? | What may the results of the oral glucose tolerance test indicate? | Why is blood sugar checked at home? | What is a hemoglobin A1c (A1c)? | What are the acute complications of diabetes mellitus? | What are the chronic complications of diabetes mellitus? | What can be done to slow diabetes complications? | How is diabetes treated? | Medications for type 2 diabetes mellitus? | Medications that increase the insulin output by the pancreas - sulfonylureas and meglitinides | Medications that decrease the amount of glucose produced by the liver | Medications that increase the sensitivity of cells to insulin | Medications that decrease the absorption of carbohydrates from the intestine | Treatment of diabetes with insulin | Different methods of delivering insulin | The future of pancreas transplantation | Diabetes Mellitus At A Glance | Diabetes Associated Bladder Dysfunction in Older Adult |

Treatment of diabetes with insulin

Insulin is the mainstay of treatment for patients with type 1 diabetes mellitus. Insulin is also important in type 2 diabetes when blood glucose levels cannot be controlled by diet, weight loss, exercise, and oral medications.

Ideally, insulin medication should be administered in a manner that mimics the natural pattern of insulin secretion by a healthy pancreas.

The complex pattern of insulin secretion by the pancreas is difficult to duplicate. Still, adequate blood glucose control can be achieved with careful attention to diet, regular exercise, home blood glucose monitoring, and multiple insulin injections throughout the day.

In the past, the insulin used was being derived from animal sources, particularly cows and pigs. Not only was there a problem with the supply of insulin meeting the demand, but beef and pork insulin also had specific problems.

Originating from animals, these types of insulin caused immune reactions in people. Patients would become intolerant or resistant to animal insulin. With the acceleration of scientific research in the latter half of this century, beef and pork insulin were replaced by human insulin.

In 1977, the gene for human insulin was cloned, and through modern technology, manufactured human insulin was made available. Human insulin is now widely used.

Insulin now comes in a variety of preparations that differ in time of onset and length of action. Because of these differences, combinations of insulin are often used to allow for a more tailored regimen of blood sugar control. The table below lists the most common types of insulin currently in use, and their specific properties.

For example, a patient may take an injection of Lente in the morning and evening to provide a baseline of insulin throughout a 24-hour period. In addition, the same patient may take an injection of Humalog just before meals to cover the increase in carbohydrate load after eating.

Different methods of delivering insulin

Not only is the variety of insulin preparations available growing, so are the methods for administering insulin.

Pre-filled insulin pens

In the past, insulin was available only in an injectable form. This involved carrying syringes (which a few decades age were made of glass and required sterilization), needles, vials of insulin, and alcohol swabs. Needless to say, patients often found it difficult to take multiple shots a day, and as a result, good blood sugar control was often compromised.

Many pharmaceutical companies are now offering discreet and convenient methods of insulin delivery.

Both Novo Nordisk and Lily have an insulin pen delivery system. This system is similar to an ink cartridge in a fountain pen. A small pen-sized device holds an insulin cartridge (usually containing 300 units). Cartridges are available in the most widely used insulin formulations, such as those listed in the table above. The amount of insulin to be injected is dialed in by turning the bottom of the pen until the required number of units is seen in the dose-viewing window. The tip of the pen consists of a needle that is replaced with each injection. A release mechanism allows the needle to penetrate just under the skin and deliver the required amount of insulin. The cartridges and needles are disposed of when finished and new ones are simply inserted. These insulin delivery devices are discreet and less cumbersome than traditional methods.

Insulin pump

The most recently available advance in insulin delivery is the insulin pump. In the United States, MiniMed, Deltec and Disetronic market the insulin pump.

An insulin pump is composed of a pump reservoir similar to that of an insulin cartridge, a battery-operated pump, and a computer chip that allows the user to control the exact amount of insulin being delivered.

Currently, pumps on the market are about the size of a beeper. The pump is attached to a thin plastic tube (an infusion set) that has a soft cannula (or needle) at the end through which insulin passes.

This cannula is inserted under the skin, usually on the abdomen. The cannula is changed every 2 days. The tubing can be disconnected from the pump while showering or swimming. The pump is used for continuous insulin delivery, 24 hours a day.

The amount of insulin is programmed and is administered at a constant rate (basal rate). Often, the amount of insulin needed over the course of 24 hours varies depending on factors like exercise, activity level, and sleep. The insulin pump allows for the user to program many different basal rates to allow for this variation in lifestyle. In addition, the user can program the pump to deliver a "bolus" during meals to cover the excess demands of carbohydrate ingestion.

Over 50,000 people worldwide are using an insulin pump. This number is growing dramatically as these devices become smaller and more user-friendly.

Insulin pumps allow for tight blood sugar control and lifestyle flexibility while minimizing the effects of low blood sugar (hypoglycemia). At present, the pump is the closest device on the market to an artificial pancreas.

Naturally, the next step would be a pump that can also sense blood sugar levels and adjust the insulin delivery accordingly. Much effort is being concentrated on this area of research and possibly, even within the next year, a prototype device will be available for trial.

Inhalation

Another promising route of insulin administration is through inhalation. Inhaled insulin is currently being tested.

Many devices are available that allow for other medications to be used in this manner, the best example of which is asthma therapy.

Insulin is not absorbed through the bronchial tubes (airways), and must reach the air sacks at the end of the bronchial tubes (alveoli) to be absorbed. Once at the alveoli, insulin can be absorbed and enter the bloodstream.

Currently, powdered inhalers and nebulizers are being studied to determine which delivery system is the most reliable. The safety of inhaled insulin still needs to be established before a product for consumer use can be made available. Trials are currently underway to establish the safety of inhaled insulin.

Intranasal, Transdermal, PILL

Other routes for the delivery of insulin have also been tried.

Intranasal insulin delivery was thought to be promising. However, this method was associated with poor absorption and nasal irritation.

Transdermal insulin (skin patch delivery) has also yielded disappointing results to date.

Insulin in pill form is also not yet effective since the digestive enzymes in the gut break it down.

The future of pancreas transplantation

Ultimately, the goal in the management of type 1 diabetes is to provide insulin therapy in a manner that mimics the natural pancreas.

Perhaps the closest therapy available at this time is a transplant of the pancreas. Several approaches to pancreatic transplantation are currently being studied, including the whole pancreas and isolated islet cells (these groups of cells contain beta cells that are responsible for insulin production).

Transplantation is not without risk. Both the surgery itself and the immunosuppression that must occur afterward pose significant risks to the patient.

For these reasons, the kidney and pancreas are usually transplanted at the same time. At present, there is disagreement about whole pancreas transplantation in patients not currently requiring kidney transplantation. The issue of whether the benefits outweigh the risks in these patients is under debate. There is also a chance that diabetes will occur in the transplanted pancreas.

Selectively transplanting islet cells is an interesting alternative to whole pancreas transplantation. However, the concern over rejection remains. Attempts to disguise the islet cells in tissues that the body won't reject (for example, by surrounding the islet cells by the patient's own cells and then implanting them) are underway.

In addition, researchers are exploring artificial barriers that can surround the islet cells, provide protection against rejection, and still allow insulin to enter the bloodstream.

The next few years promise to be an exciting time in diabetes care. Many agents for the treatment of type 2 diabetes are under development and the options for insulin therapy continue to grow and methods for insulin delivery continue to become more refined.

While research continues to expand in these areas, one thing remains constant. Achieving the best blood sugar control possible remains the ultimate goal in both type 1 and type 2 diabetes.

We now know, beyond a doubt, that good blood sugar control minimizes the long-term complications of diabetes, including blindness, nerve damage, and kidney damage.

Finally, a healthy lifestyle can do nothing bad…it should remain the cornerstone of management for diabetes.

Diabetes Mellitus At A Glance

• Diabetes mellitus is a chronic condition associated with abnormally high levels of sugar (glucose) in the blood.

• Insulin produced by the pancreas lowers blood glucose.

• Absence or insufficient production of insulin causes diabetes.

• The two types of diabetes are referred to as type 1 (insulin dependent) and type 2 (non-insulin dependent).

• Symptoms of diabetes mellitus include increased urine output, thirst and hunger as well as fatigue.

• Diabetes mellitus is diagnosed by blood sugar (glucose) testing.

• The major complications of diabetes mellitus are both acute and chronic. Acutely: dangerously elevated blood sugar, abnormally low blood sugar due to diabetes medications may occur. Chronically: disease of the blood vessels (both small and large) which can damage the eye, kidneys, nerves, and heart may occur

• Diabetes treatment depends on the type and severity of the diabetes. Type 1 diabetes mellitus is treated with insulin, exercise, and a diabetic diet. Type 2 diabetes mellitus is first treated with weight reduction, a diabetic diet, and exercise. When these measures fail to control the elevated blood sugars, oral medications are used. If oral medications are still insufficient, insulin medications are considered.