Chapter 64: Diabetes

INTRODUCTION

Diabetes is an important chronic disease 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. 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 diabetes) which comprises about 10% of all cases, and type 2 diabetes (formerly referred to as non-insulin-dependent 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 destroy 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. 64-1.

The other potential precursor to type 2 diabetes is the metabolic syndrome. The metabolic syndrome represents a set of risk factors that predispose individuals to both cardiovascular disease and diabetes. Metabolic syndrome factors include abdominal obesity, atherogenic dyslipidemia (elevated triglyceride levels, smaller LDL particle size, and low HDL cholesterol), raised blood pressure, insulin resistance (with or without glucose intolerance) and prothrombotic and proinflammatory states. The metabolic syndrome is associated with the prediction of both diabetes and cardiovascular disease independent of other factors.⁴ It is hypothesized that clinical improvement in these factors may prevent or delay the onset of diabetes and cardiovascular disease.

DIAGNOSIS

The diagnosis of type 1 diabetes is ...