Diabetes

Diabetes is a generic term relating to conditions that are characterized by hyperglycemia. In recent decades understanding of underlying causes and pathological mechanisms leading to diabetes has progressed considerably. It made possible distinguishing between different forms of the disease, sometimes tracing the cause to the single defective gene.

Long-term diabetes has detrimental effects on numerous organs of the body, but the organ chiefly affected is the endothelium - the lining of all blood vessels. This becomes leaky and damage to other organs results from this.

Traditionally the goal of treatment was striving to achieve the best possible control of the blood glucose level, but more recent thinking in Type 2 Diabetes stresses also the need for more stringent blood pressure control. The aim is to avoid or minimise diabetic complications. At the same time, general well-being of the person affected with diabetes is important. According to the latest guidelines, life of diabetics should be as much as possible like that of persons without the disease.

Etymology

"Diabetes" is a Greek word meaning "a passer through; a siphon". "Mellitus" comes from the Greek word "sweet". Apparently, the Greeks named it thus because the excessive amounts of urine that a diabetic (when in a hyperglycemic state) would excrete attracted flies and bees because of the glucose content.

Passing abnormal amounts of urine can be a main symptom of several diseases (most commonly of the kidneys, but the word diabetes is connected with two different diseases: diabetes insipidus and diabetes mellitus).

Causes

The general underlying feature of diabetes is hyperglycemia. This arises from a complex of causes and includes defficiency of insulin or resistance to its action - Insulin resistance. Insulin is produced in the endocrine part of the pancreas, consisting of clumps of specialised cells scattered throughout the exocrine Pancreas. One cause therefore of insulin-dependent diabetes is pancreatic disease such as pancreatitis and cystic fibrosis.

For the purposes of this writeup, we are referring to diabetes mellitus. There are two different types of diabetes mellitus - type 1 (previously juvenile diabetes), generally found in children and adolescents, and type 2 (previously adult onset diabetes mellitus). A third type of diabetes, gestational diabetes mellitus is common during pregnancy.

Insulin is a hormone that enables glucose molecules to enter the cells and to be metabolized. The brain requires many things to function correctly, but two things are of the utmost importance to a healthy, working brain: oxygen and glucose. Without glucose, brain function is impaired, the level of consciousness is altered, physiological functions are impaired, and ultimately, the patient with Hypoglycemia (too little glucose) will die if untreated.

Patients with hyperglycemia (too much glucose) also will eventually die without treatment for the same basic reason: glucose cannot get into the cells. However, with hyperglycemia, it is because there is no insulin to let the glucose be metabolized, whereas in hypoglycemia there is no glucose to be metabolized.

Currently, the exact cause of all types of diabetes has not been fully discovered. Both types of diabetes can be genetically linked. In Type 1 diabetes, the body's immune system attacks the beta cells of the islets of Langerhas in the pancreas that results in destruction of hormone producing cells preventing it from producing enough insulin. In Type 2 diabetes the body simply does not produce enough insulin to meet demands, insulin actions are diminished or a combination of the two.

In both of these cases there is usually some secondary cause which triggers the body's malfunction. Type 1 diabetes may be triggered by disease, stress, or poisons in the environment. There is clearly a genetic element in the susceptibility of individuals to some of these triggers. Type 2 is most often triggered by obesity, which is found in approximately 85% of patients diagnosed with that form of the disease. Age is also thought to be a contributing factor, though the exact reason for this is unknown.

Types

According to 1999 WHO Classification of diabetes mellitus we can distinguish :

Type 1
- Autoimmune (immune-mediated)
- Idiopathic
Type 2 (with variable components of insulin secretory defect and insulin resistance)
Gestational diabetes mellitus

The use of terms and acronyms "insulin-dependent diabetes mellitus" (IDDM) and "non-insulin-dependent diabetes" (NIDDM) is not recommended. The recognition of a form of diabetes caused by malnutrition or protein deficiency was challenged and awaits further review. "Type I" and "Type II" has been replaced with "Type 1" and "Type 2" equivalents.

With Type 1 diabetes, the patient must take insulin every day (usually by injection), since the pancreas does not produce insulin. With Type 2 diabetes, the level of blood sugar can often (but not always) be regulated through diet, exercise, and/or medications that boost insulin production or decrease insulin resistance.

Presentation (signs and symptoms)

Hyperglycemia

Relative deficit of insulin compared to glucose. Hyperglycemia may lead to "diabetic coma".

In Type two Diabetes there is a slow onset, but in type one, particularly in children, onset may be alarmingly fast. The thirst developes because of osmotic effects - glucose leaking into the urine carries water with it.

Glucose entry to the cells is greatly impared, and so the body thinks that it is getting no sustenance and moves onto a famine economy. Beside diabetic coma is another major complication Diabetic ketoacidosis (DKA). With DKA, the byproducts of the excess blood glucose levels (in DKA, at least 250 mg/dL or 13.9 mmol/l) are ketone bodies (acetone for example). This state produces acidosis - the pH of the blood lowered - and the body tries to compensate by reducing the Carbon Dioxide tension in the blood through increasing the volume of air brought in and out of the lungs per minute. When this is considerable it is sometimes referred to as Kussmaul respirations - another medical eponym, Kussmaul presumably being the first physician to report it in recognisable form.

Polyuria (excessive and frequent urination).
Polydipsia (excessive thirst and fluid intake).
Polyphagia (extreme hunger).
Unusual weight loss (when hyperglycemic for some time)
Flu-like signs and symptoms, may manifest as fatigue.
Sweet, fruity (alcohol-like) odor (of acetone and ketones) on breath. (This is a classic, hallmark sign.)
Kussmaul respirations (rapid, deep respirations).
Altered level of consciousness (eventually leading to coma).

Prognosis

Possible Complications

Two general conditions can result as a result of diabetes (as far as blood sugar is concerned): too little glucose (hypoglycemia) and too much glucose (hyperglycemia). Both conditions are dangerous and somewhat similar in presentation.

Some effects, such as hypoglycemia, can happen any time. Others develop when a person has had diabetes for a long time. These include damage to the retina of the eye (diabetic retinopathy), the blood vessels (angiopathy), the nervous system (neuropathy), and the kidneys (nephropathy).

Treatment

There are several different ways of delivering drugs for treating Type 1 diabetes: insulin injections, insulin pump, pills, and implants. Common drugs include Glucophage, Orinase, Diabinase, and Tolinase.

Studies show that keeping blood glucose levels as close to the normal, nondiabetic range as possible may help prevent, slow, or delay harmful effects to the eyes, kidneys, and nerves. This has to be undertaken with care and keeping blood glucose levels lower leaves less room for error and increases the possibility of a hypoglycemic episode.

Complications of treatment

Hypoglycemia

Hypoglycemia means an excessively low blood glucose level. It arises in Diabetes from a relative excess of Insulin over food. On days when for whatever reason less food can be taken than usual a small reduction in Insulin dose is usually necessary to avoid hypoglycaemia, but it is dangerous to omit the Insulin altogether since this risks hyperglycaemia or diabetic ketoacidosis.

The most common cuase of reduced food intake is intercurrent illness, and al diabetics should have "sick day rules" to hand in order to decide what to do when this happens.

Public Health, Policy and Health Economics

The Declaration of St Vincent was the result of international efforts to improve the care accorded to diabetics. Diabetes is enormously expensive for healthcare systems and States. Work in the Puget Sound area of N. America suggested that the activity of holding a minimum dataset and keeping this up to date for all diabetics was associated with a reduction in cost of 1000 US Dollars per year in the cost of care per diabetic per year for the rest of their life. Recognition of this drove the Hawkes Bay initiative which established such a system, and resulted in various activities throughout the world including the Black Sea Telediab project which produced elements of a distributed diabetic record and management system as an open source computer program.

Please see hypoglycemia article for more information.

References

"Conditions in Occupational Therapy: effect on occupational performance." ed. Ruth A. Hansen and Ben Atchison (Baltimore: Lippincott Williams & Williams, 2000), 298-309. ISBN 0-683-30417-8