Symptoms and Signs:DM is a syndrome characterized by a high level of glucose in the bloodstream due to a defect of insulin secretion, action, or both. It has metabolic, vascular, and neuropathic components. Heredity is considered an important factor, although diet and lifestyle also play and important role. If you have a relative with diabetes, you are 2.5 times more likely to develop the disease than the general population. It is also interesting to note that 85% of diabetics have been obese at one time. African Americans, Hispanics, Native Americans, Asian Americans and Pacific Islanders are also at greater risk for developing DM, except for Type 1 diabetes which is more prevalent among whites (Bellenir).
Glucose is the body's primary source of energy. Insulin is a hormone produced and secreted by b-cells of the pancreas which helps transport glucose into cells. Insulin also helps to convert glucose into glycogen for long-term storage in the liver. When insulin is deficient, glycogen is not produced and glucose is not absorbed or used by the cells. The glucose accumulates in large quantities in the blood (hyperglycemia) and in the urine (glycosuria). Along with a large amount of glucose being lost in the urine, water and electrolytes are lost as well. Since glucose is unavailable for energy production in the cells, fats and proteins are used instead. Ironically, in order to metabolize fat properly, it must be metabolized with a certain proportion of carbohydrate (glucose) at the same time. If the glucose is not available, as is the case in DM, incomplete metabolism of fat occurs. This causes an accumulation of toxic substances, known as ketone bodies, in the bloodstream leading to a state of ketoacidosis, or ketosis. If left untreated, it can result in coma and death.
DM has been divided into five different "types".
Type 1 Diabetes Mellitus
Type 1 diabetes mellitus is also called insulin-dependent diabetes mellitus (IDDM) or juvenile-onset diabetes mellitus. IDDM is considered an autoimmune disease with little to no insulin production. It is defined by the presence of ketosis. These diabetics require daily injections of insulin to survive. Symptoms include increased thirst, increased urination, constant hunger, weight loss, blurred vision, and extreme tiredness. These symptoms develop over a short period of time, but destruction begins years earlier. Hereditary factors increase the risk of developing IDDM, but environmental factors are thought to be involved as the trigger.
There is some evidence that infection with certain viruses may be implicated in the etiology for some cases of IDDM. The hypothesis is that viruses may act as triggers for the autoimmune process that attack and destroy b-cells of the pancreas, or they are the primary cause of injury to b-cells. Coxsackie virus, EMC (encephalomyocarditis) virus, rubella virus, some retroviruses, and the virus that causes mumps are all being considered in this respect. Much further investigation is needed.
It has also been postulated that increased cow milk consumption may increase the incidence of IDDM. There are two major types of protein in milk, whey and casein. The A1 and A2 variants of b-casein are the most common in most cow breeds. A study by R.B. Elliott et al. Suggests that consumption of milk that is high in the A1 and B variants of b-casein may be involved in the etiology of IDDM due to the possible immunosuppressant properties of these proteins. Of the countries that were involved in the study, generally the more milk consumed in a country, the higher the incidence of IDDM with one very notable exception. Despite the high consumption of milk in Iceland, the country experienced a very low incidence of IDDM. It was found that the milk in Iceland had the lowest A1 and B variant b-casein levels of all the countries studied.
There are a number of other studies that connect the consumption of certain foods with an increased risk of the development of IDDM. Some epidemiological studies suggest that breast-fed infants have a lower risk of developing IDDM, and that a long duration of breast-feeding offers greater protection. This could be due to the content of immunoglobulin A (IgA) antibodies and cytotoxic T- and B-lymphocytes that protect against infection. It could also be that early cessation of breast-feeding generally means an early introduction of cow's milk into the diet. Other studies show and increased risk of developing IDDM with consumption of protein-rich foods (particularly from meat), because the high protein content stimulates b-cells in the pancreas. This seems to also be true for foods that are high in nitrosamines. A high caloric intake during the early years of life has also been implicated in this regard.
Type 2 Diabetes Mellitus / Non-Insulin-Dependent Diabetes Mellitus (NIDDM)
The second type of diabetes is called type 2 diabetes mellitus or non-insulin-dependent diabetes mellitus (NIDDM). The latter name is somewhat misleading because up to 25% of people with this form of DM require insulin. It is the most common form of diabetes; 90-95% of all diabetics have type 2. These diabetics have some effective insulin with an absence of ketosis. Eighty to ninety percent of these individuals are overweight. It usually present in adults 40 years of age and older. When it occurs in the young it is often called maturity-onset diabetes of youth (MODY). Obesity, advancing age, and a high fat diet are risk factors. Type 2 diabetes is a major health problem associated with high morbidity and mortality, and high health care cost.
The symptoms of NIDDM usually develop gradually, and are not as noticeable as those of Type 1 DM. Symptoms include excessive urination (polyuria), unusual thirst, weight loss, blurred vision, frequent infections, slow healing of sores, glycosuria, hyperglycemia, and excessive hunger. These diabetics often feel tired, ill, or weak, and their urine is usually pale due to the large amount of water excreted.
At first, there is normal insulin output from the pancreas. However, the cells of the body are said to be insulin resistant. This can occur because of intrinsic defects in insulin receptors on the cell surface, such that insulin cannot bind to them and get glucose into the cell. It can also be due to anti-insulin antibodies, which render the insulin unusable, or due to accelerated rates of breakdown of the insulin molecule. Regardless of the reason, the insulin resistance results in ineffective use of insulin. The result is a condition of impaired glucose tolerance (IGT) and hyperglycemia. IGT increases the risk of developing NIDDM and cardiovascular disease. The prevalence of IGT in adults is 11 to 20 percent in North America (incidentally, that number is 3 to 10 percent in Europe). A large number of people with IGT go on to develop NIDDM via the following process. The pancreas produces more insulin to make up for the high blood glucose levels. This can cause a decrease in the number of receptors that are expressed on cell surfaces (down-regulation) and hyperinsulinemia results. The b-cells become exhausted in the effort and diabetes results.
Gestational Diabetes Mellitus (GDM)
Gestational diabetes mellitus (GDM) is the third type of diabetes. It affects two to five percent of all pregnancies. It is considered an abnormality of glucose tolerance that occurs during pregnancy. This type of diabetes usually disappears when the pregnancy is over, but these women have a higher risk of developing NIDDM within the next 10 to 15 years after the end of the pregnancy. It is associated with a high risk of fetal and maternal morbidity and adverse peri-natal outcomes.
During a normal pregnancy, the placenta produces insulin antagonistic hormones (anti-insulin hormones). This increases the mother's requirement for insulin. In some women, this increased demand cannot be met by the b-cells, and abnormal carbohydrate metabolism results, thus diabetes. Hyperglycemia and hyperinsulinemia are both detrimental to the fetus. High maternal blood glucose can lead to a large or heavy baby of its gestational age, congenital abnormalities, spontaneous abortion, or miscarriage. Delivery complications may arise such as shoulder dystocia, brachial plexus injuries, hypoglycemia, hypocalcemia, hyperbilirunemia, and polycythemia (McMahon et al.). Women with GDM have an increased risk of developing preeclampsia, urinary tract infections, polyhydraminos, oligolydraminos, and uterine bleeding of unknown origin (McMahon et al.).
The risk factors for developing GDM include a family history of DM, obesity, previous GDM, advancing maternal age, previous low birth weight or high birth weight infant, previous stillbirth, previous spontaneous or induced abortion, and chronic hypertension (McMahon et al.). Post-partum, these women are re-assessed and defined as having either a previous abnormality of glucose tolerance IGT, or DM.
Malnutrition-Related Diabetes Mellitus
The World Health Organization (WHO) has recently defined a category called malnutrition-related diabetes mellitus. The age of onset is usually between 10 and 40 years of age. It is predominately found in under-developed countries. Symptoms include polyuria, polydypsia, and weight loss. These diabetics usually require insulin to control their diabetes, but they do not develop ketosis, regardless of whether or not they receive appropriate treatment. The role of malnutrition in the etiology of this type of diabetes is still unknown.
Other Types / Secondary Diabetes Mellitus
The final category of diabetes is called other types or secondary diabetes mellitus. This category includes all other possibilities for having DM. They include diseases of the pancreas that destroy b-cells such as pancreatitis and cystic fibrosis. Hormonal syndromes, such as Cushing's syndrome or acromegaly, which interfere with insulin secretion or action, can also lead to diabetes. There is another condition called iatrogenic or drug-induced diabetes caused by drugs that can interfere with insulin secretion or action. These drugs include phenytoin, glucocorticoids, estrogen, some diuretics and antihypertensives. This condition usually disappears when drug use is discontinued. Some people suffer from rare conditions involving abnormalities of the insulin receptor, rendering the insulin ineffective. There are also a variety of rare genetic syndromes in which DM occurs more frequently than in the general population for reasons yet to be understood. Some people produce autoantibodies that attach to and block insulin receptors. Recently, there have been several families described in which point mutations have been identifies in the insulin gene which causes amino acid substitutions at the receptor binding site on the insulin molecule. The insulin cannot bind to the cells to transport glucose into the cell for use.
Causes:
See categorical sections in Symptoms and Signs, above.
What to Expect:
The complications that can occur with uncontrolled DM can be quite severe, affecting a variety of different organ systems throughout the body. Chronic hyperinsulinemia and insulin resistance can play a role in the development of atherosclerosis, essential or primary hypertension, cardiovascular disease, and some forms of obesity. Heart disease is the leading cause of diabetes-related deaths. It you have diabetes you are two to four times more likely to develop heart disease than the general population. You also have a two to four time greater risk of having a stroke. Sixty to sixty-five percent of diabetics also have high blood pressure. Elevated serum cholesterol levels can lead can lead to gall stone formation and atherosclerosis. If the atherosclerosis progresses far enough, occlusion of blood vessels of the limbs can result in gangrene, while occlusion of the vessels of the heart can cause a myocardial infarction, and those of the brain, stroke.
Many people with DM develop changes in the small blood vessels, especially those of the retina and kidneys, leading to retinopathy and kidney disease respectively. DM is the leading cause of end-stage renal disease, and 40 percent of all new cases of kidney disease are due to diabetes. DM is also the leading cause of new cases of blindness in adults 20 to 74 years of age.
Sixty to seventy percent of diabetics develop some form of nerve damage. This manifests as numbness and tingling or pain to the feet and hands, loss of motor skills, slowed digestion, carpal tunnel syndrome, and other neuropathies. Severe forms of diabetic nerve disease are a major contributing cause of lower limb amputations. More than half of all amputations in the US occur among people with DM.
Other complications of diabetes include itching, boils, and arteriosclerosis. Periodontal disease occurs more frequently and severely for diabetics; it develops in 30% of people 19 years or older with IDDM. Diabetics are also more susceptible to other illnesses and are more likely to die of pneumonia or influenza.
Several problems can occur with diabetic women who are pregnant (these figures do not include those who develop GDM). The rate of major congenital malformation in babies born to women with pre-existing diabetes is from 0 to 5 percent in women with pre-conception care, to up to 10 percent for women with no pre-conception care. Also, three to five percent.
