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Diabetes and other metabolic disorders, such as thyroid disease, Chushing’s syndrome, and polycystic ovary syndrome (PCOS) are important chronic diseases both in terms of the number of persons affected and the considerable associated morbidity and early mortality. In this review, we will focus on the epidemiology and public health implications of diabetes, with an additional section for a brief discussion of thyroid disease, Cushing’s syndrome, and PCOS.


Diabetes is a chronic disease in which there is a deficiency in the action of the hormone insulin. This may result from a quantitative deficiency of insulin, an abnormal insulin level, resistance to its action, or a combination of deficits. Two major forms of the disease are recognized: type 1 diabetes (formerly referred to as insulin-dependent or juvenile diabetes) which comprises about 10% of all cases, and type 2 diabetes (formerly referred to as noninsulin-dependent or adult-onset diabetes), which accounts for about 90% of the cases. Type 2 diabetes may occasionally occur as a result of other diseases such as acromegaly and Cushing’s syndrome. Metabolic disorders such as hemochromatosis, can also cause the disease. Diabetes can also be drug induced, for example, by steroids and possibly by the thiazide diuretics and oral contraceptives. Finally, diabetes may occur secondary to disease processes directly affecting the pancreas, such as cancer or chronic pancreatitis, which destroys the insulin-producing beta cells in the pancreatic islets (of Langerhans). However, these are relatively rare causes of diabetes.

In addition to these primary and secondary types of diabetes, two further classifications of abnormalities of glucose tolerance are of note. Gestational diabetes occurs during pregnancy but typically remits shortly after delivery. Impaired glucose tolerance (IGT) or impaired fasting glucose (IFG), now termed “prediabetes,” are conditions in which blood glucose is elevated but not high enough to be classified as diabetes. Nonetheless, these conditions may carry some increased risk of large vessel (e.g., coronary heart) disease.1 Both gestational diabetes2 and prediabetes3 carry an increased risk for the subsequent development of type 2 diabetes. The types of diabetes and clinical stages are outlined in Fig. 53-1.

Figure 53-1

Disorders of glycemia: etiological types and clinical stages. In rare instances patients in these categories (e.g., Vacor Toxicity, Type 1 presenting in pregnancy, etc.) may require insulin for survival. (Source: Adapted with Permission from Classification Of Diabetes Mellitus 2019, World Health Organization.)


The diagnosis of type 1 diabetes is fairly straightforward. Type 1 diabetes often, though by no means always, has its onset in childhood. Classically, the child will have symptoms of excessive thirst (polydipsia), excessive urination (polyuria), and weight loss. In a child with high blood glucose, these symptoms almost invariably point to type 1 diabetes. These patients lose virtually all capacity to produce insulin and without ...

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