Types of Diabetes Although in the large majority of cases, the cause of diabetes remains obscure, there are patients in whom the onset of diabetes is secondary to some other disorder. These cases are known as secondary diabetes. For example, a tumor or growth of the pancreas gland may necessitate pancreatectomy, or removal of the pancreas by surgical operation. In such cases, since there is no production of insulin, diabetes inevitably results. The pancreas can also be destroyed by various disorders which lead to fibrosis, or scarring of all the islet cells of the pancreas, as may occur in an ailment known as haemochrornatosis. Here too, diabetes inevitably results as a secondary effect of islet cell destruction. Several hormones antagonize the action of insulin and if these are produced in excess, the effect of insulin may be swamped and diabetes will result. At least five hormones counteract the effect of insulin and so lead to abnormal elevation of the level of sugar in the blood. Excessive production of growth hormone leads to a condition called gigantism when this occurs before puberty and acromegaly when it happens in the adult. Growth hormone is produced by the pituitary gland, a small bean-shaped organ lying below the brain. It is responsible for the growth and development of the child and if it fails, the child fails to grow and remains a perpetual Peter Pan. If the reverse occurs and excessive growth hormone is produced by the pituitary the child grows to an excessive height, perhaps over 7 ft. tall. Since growth hormone antagonizes the effect of insulin, a high proportion of these giants develop diabetes. If excess growth hormone occurs in the adult, the condition of acromegaly appears in which the features become coarse and thickened and the hands and feet become steadily broader and larger. Here again, about a third of patients with acromegaly develop diabetes due to elevation of the blood sugar by excess growth hormone. Another hormone which antagonizes insulin is cortisol. Cortisol is produced by the adrenal glands. These organs lie above the kidneys and if they overact, excess cortisol leads to high blood pressure and diabetes. Cortisol damps down the effects of inflammation and is prescribed in tablet form to patients suffering from various inflammatory ailments, such as rheumatism or asthma. In such patients, if the dose of cortisol is too high or if treatment is prolonged, diabetes is liable to occur, since the action of insulin is suppressed. Of much interest in recent years has been the demonstration that the contraceptive pill leads to a deterioration of glucose tolerance. If the glucose tolerance test is performed in women starting the pill and is then repeated after about a year, the blood sugar levels after taking glucose are somewhat higher than those taken originally. In other words, the pill creates a tendency towards diabetes. In practice, it is quite unusual for those taking the pill ever to develop actual diabetes and it can be argued that the changes in glucose tolerance are of no material significance in the vast majority of women taking these preparations for contraceptive purposes. The pill contains an oestrogenic compound, a synthetic preparation of the natural hormone produced by the ovaries, and it is probably this hormone which exerts this effect. It is well known that oestrogens tend to lead to an increase in weight and this in itself might impair glucose tolerance but the effect is not confined to those women who put on weight. At most it could be said that in women with a tendency to diabetes, taking the pill could make matters worse. Apart from hormones, some drugs given for the treatment of various ailments may damage the islet cells and inhibit production of insulin. This is particularly true of the chlorothiazide group of diuretics. Diuretics are given to increase the output of fluid from the body and are of special value in heart disease when the circulation is impaired. The body may become waterlogged due to this circulatory failure and swelling of the legs occurs. Diuretics encourage an increased output of fluid by the kidneys and so are enormously helpful in relieving congestion due to the impairment of the circulation. However, an unfortunate effect is that diabetes may result, since chiorothiazide causes gradual suppression of the islet cell production of insulin. This is a small price to pay for the improvement that diuretics can give to patients with heart trouble. In the vast majority of diabetics, no cause can be found for the onset of their ailment. In young people, it is often suspected that there may have been mechanical destruction of the islet cells by a virus infection and rarely diabetes has been known to follow an attack of mumps. Mostly, however, no such evidence exists. For the purposes of classification, diabetes can be divided into two types: I. Mild diabetes occurring in middle-aged people, frequently associated with obesity. In this type of diabetes, symptoms are usually mild or nonexistent so that the diagnosis is often made by the chance finding of sugar in the urine at a routine medical examination. Once the diagnosis is confirmed, these patients are easily restored to normal health by a reduction of food intake. This relieves the demands placed on the pancreas. II. Production of insulin becomes adequate to store excess sugar as glycogen, since it no longer has to lay down excess deposition of fat. If simple restriction of diet is not enough, tablets may be given which stimulate the pancreas to produce more insulin. Usually, diabetes of this sort is easy to control and with a co-operative patient the expectation of life and health should not be unduly impaired. The urine contains sugar but only rarely contains acetone. Consequently, diabetic coma is very unusual in this type of patient. 2. Severe diabetes can occur at any age lit is typified by that occurring in children or young people. The onset of diabetes in these cases is generally more sudden and the symptoms, which are dealt with later, much more severe. These patients have lost a lot of weight and are usually very thin. The urine contains sugar and, what is more significant acetone as well. Without insulin, expectation of life would be very restricted and coma would soon ensue. These are the patients to whom insulin offers health and activity. Although these two types of diabetes may seem quite different, in fact no clear delineation can be made. A mild obese diabetic woman can have a child who develops acute diabetes. They are differentiated by their need for insulin. Thin, young diabetics invariably need insulin, whereas it is quite exceptional for obese diabetics to need it.