Type 2 Diabetes Mellitus
Diabetes mellitus is one of the most common diseases in the world. It affects 2.8% of the world population. Of all diabetic patients, 80-90% suffers from type 2 diabetes. The disease usually manifests after the age of 40, most commonly around the age of 55. The number of cases is steadily increasing; scientists believe that in 15 years the number of patients will double. Worldwide, there are vast differences in the incidence of this disease-- for instance, certain Native American tribes exhibit a high incidence while in some African territories the incidence is low. These differences can be accounted for by different genetic predispositions as well as different environmental influences.
Type 2 diabetes mellitus (T2DM) is a chronic disease characterised by a disturbance in glucose metabolism. Glucose is the main fuel for the human body. The reason for the appearance of type 2 diabetes mellitus is a decreased effect of insulin on the cells, leading to the decreased transport of glucose from blood to the inside of cells. The result is an increased blood glucose concentration and a lack of glucose in the body cells.
Type 2 diabetes mellitus appears due to a decreased action and effect of insulin on the cells. This may be reflected on three levels:
As a defective secretion of insulin from the pancreas,
As a cellular resistance to insulin,
As a defective secretion of glucose from the liver.
It is not entirely clear why a diminished insulin sensitivity develops. Genes apparently play an important role--the incidence of the disease in identical twins is almost 100%. However, besides genetic reasons some other risk factors also contribute to the development of type 2 diabetes mellitus, such as obesity (the more fat tissue in the body, the more resistant the cells become to the effects of insulin), insufficient physical activity, a family history of diabetes, gestational diabetes as well as pre-diabetes. Pre-diabetes is a condition in which the blood sugar level is higher than normal, but not high enough to be classified as type 2 diabetes mellitus.
The signs and symptoms of diabetes can be very unspecific at first sight. Many years may pass before a diagnosis is made. The signs of diabetes are the result of hyperglycaemia which means an increased blood sugar concentration. The symptoms include increased thirst and frequent urination, insatiable appetite, weight loss, fatigue, visual disturbances and slowly healing wounds. The complications of type 2 diabetes mellitus develop over a lengthy time period. The sooner the disease is discovered, the lower the risk of complications which include cardiovascular diseases (atherosclerotic coronary artery disease, myocardial infarction and hypertension), nerve lesions (neuropathy -- the patients feel prickling and numbness, a burning feeling or pain), kidney disorders (in the late stage, complications may include kidney failure which is treated by a kidney transplant), lesions in the eyes (blindness may result), lesions of the foot soles (an amputation may become necessary), osteoporosis and Alzheimer's disease.
To check for this disease, the standard first thing to do is to take a detailed history of the patient's complaints. Based on the description of the complaints, the physician will soon suspect diabetes mellitus. However, in order to prove it unequivocally, a laboratory blood test must be performed to show an increased blood sugar level. To that effect, an oral glucose tolerance test (OGTT) is most often performed which involves measuring the blood sugar concentration after the patient has ingested a specifically determined amount of glucose.
A healthy diet – Your diet should include a wide variety of foods and should suit your taste. Eat many lighter meals instead of a few heavier ones. The meals should just about cover your daily energy requirements (and not exceed them). You may determine your daily requirements by multiplying your normal weight (you can calculate your normal weight by subtracting 100 from your height in cm; women have to subtract additional 10%) by a factor of 32 if you only engage in light physical work, by a factor of 40 if you engage in moderate physical work or by 48 for strenuous physical work.
The diet should include a lot of fruits, vegetables and dietary fibbers that slow down the absorption of carbohydrates. Avoid alcohol for it is rich in calories and it inhibits the formation of glucose in the liver and increases the danger of a hypoglycaemia (i.e. an excessive reduction of the blood sugar level).
Physical activity – try to be active enough to induce perspiration for at least 30 minutes a day on most days of the week. High-endurance aerobic activity should be your priority (cycling, fast walking, running, swimming, etc.)
Maintenance of a normal body weight - maintenance of a normal body weight or weight reduction facilitates prevention of the disease and reduces its rate of progression. It is most important to take a holistic approach towards instituting changes in the dietary and physical activity habits, and make them a part of one's lifestyle.
Your family doctor can provide you with detailed guidelines for a right diet, physical activity and body mass maintenance. If you wish, (s)he may also refer you to a special workshop where you can acquire knowledge and practical skills regarding a healthy lifestyle. In addition to the listed recommendations, measures that aid in the normalisation of blood pressure and fat metabolism need to be taken into account.
Therapy of T2DM primarily includes the measures listed under prevention. If they do not suffice, medications need to be considered. Many patients require insulin therapy as well.
The goal of all measures is to maintain the blood glucose concentration as close to normal values as possible. In this way, the appearance of the acute and chronic complications of diabetes mellitus can be prevented or slowed down.
Measurement of blood glucose concentration may be carried out once daily or a few times per week, depending on your plan and previous course of therapy (short-term control). Measurements are carried out with the use of portable measuring devices that require only a drop of blood drawn from the finger, and are thus very convenient.
In some patients, the control over diabetes mellitus may be achieved merely with a right diet as well as regular physical exercise and body weight normalisation. In cases when this alone does not suffice, one needs to consider the use of efficient medications.
There are many categories of medications – oral hypoglycaemic agents:
Biguanides (e.g. metformin) – slow down the intestinal absorption of glucose, inhibit de novo formation of glucose in the liver, increase the sensitivity of muscle cells to insulin and insulin uptake into the muscle cells, and reduce the appetite (they are the drug of choice for the overweight T2DM patients, and do not cause bouts of hypoglycaemia).
Derivatives of sulfonylurea (sulfonylureas, e.g. glibenclamide, glimepiride and the novel analogues, the so called glinides, e.g. repaglinide, nateglinide) – they exert their effect on the pancreas and increase the sensitivity of the beta cells to glucose, thereby increasing insulin secretion; glucose concentration usually normalizes; however, the metabolic syndrome tends to worsen due to the increased insulin secretion, and one must therefore necessarily effect a lifestyle change.
Glitazones (also called thiazolidenediones, e.g. pioglitazone, rosiglitazone) – increase the sensitivity of insulin-dependent tissues to insulin.
Alpha-glucosidase inhibitors (e.g. acarbose, miglitol) – affect the intestinal enzymes (glucoamylase, sacharase, maltase) that regulate the breakdown of carbohydrates, which is an important step prior to absorption. The net effect of the inhibition of these enzymes is a reduced and slowed-down absorption of glucose; the complex sugars increase the secretion of the so called incretin GLP-1 that increases insulin secretion from the beta cells; similar effects may only be obtained by consuming foods rich in dietary fibres.
Despite the above mentioned measures, the end result is the "beta cell exhaustion" and an inability to secrete enough insulin, especially in the late phase of the disease. Thus, many T2DM patients require insulin as part of the therapy.