Artificial endocrine pancreas.

Abstract

Diabetes and its complications are a significant cause of morbidity and mortality in the world. Patients with diabetes have an excess risk of mortality compared with the nondiabetic population. Mortality rates are 41.8% for the diabetic population and 10.1% for the nondiabetic population. Among the diabetic population, the most common cause of death is cardiovascular disease, which accounts for 49.1% of deaths. The amount of life-years lost for patients with diabetes is strongly related to age at diagnosis and is a means of expressing mortality without relying on accurate prevalence data. The prevalence of physician-diagnosed diabetes has been steadily increasing in the US population, based on national household interview surveys conducted during the past 40 years. The prevalence of diagnosed diabetes from 1988 to 1994 was estimated to be 5.1% for US adults 20 years of age and older (10.2 million people when extrapolated to the 1997 US population). There were similar rates of diabetes for men and women. Based on American Diabetes Association criteria, the prevalence of diabetes (diagnosed plus undiagnosed) in people 40 to 74 years of age increased from 8.9% in the period 1976 to 1980 to 12.3% by 1988 to 1994. The prevalence of diabetes rose from 4.9% in 1990 to 6.5% in 1998. Increases were observed in both genders, all ages, all ethnic groups, all education levels, and nearly all states in the US. Many factors influence the prevalence of diabetes, including the development of new cases of diabetes and those that affect mortality from diabetes. High rates of abnormal fasting and postchallenge glucose, together with the increasing frequency of obesity and sedentary lifestyles in the population, make it likely that diabetes will continue to be a major health problem in the US. The prevalence of hypertension, hyperlipidemia, and the incidence of and mortality from heart disease and stroke are markedly declining in the US, but the prevalence of diabetes remains high. A similar increase also has been found world-wide. Diabetic complications such as neuropathy, retinopathy, nephropathy, and cardiovascular disease continue to pose major health risks for diabetic patients. Longterm complications associated with diabetes may result from a lack of blood glucose control. Consequently, much effort has focused on approaches that could replace conventional insulin therapy and provide more precise regulation of blood glucose levels. Indeed, the Diabetes Control and Complications Trial has conclusively demonstrated that improved metabolic control of glucose leads to the reduction in the rate of microvascular complications of diabetes. Conventional insulin treatment of diabetes mellitus does not prevent the vascular complications associated with longterm disease. To solve these problems, much investigation is conducted toward developing a means to provide near-physiologic insulin administration. Table 1 shows various treatments for diabetic patients. There are advantages and disadvantages to these treatments, which include pancreas transplants, islet or beta-cell transplants, hybrid devices in which the islet or beta cells are contained within permeable membranes, and a totally artificial endocrine pancreas (electromechanical artificial pancreas) that consists of a glucose sensor, a computer, and a pumping device. Biologic approaches are expected to fulfill all the endocrine functions of the normal pancreas, but at great expense; mechanical approaches fall short of total endocrine replacement but offer the substantial advantages of mass production. Each approach has inherent problems, and none is available for widespread clinical use now. So in general, many diabetic patients receive daily injections of insulin and face a high degree of compliance with a strict regimen of diet and exercise. Intensive insulin therapy is also usually associated with clinical problems including severe hypoglycemia and inherent instability of glucose control from the open-loop control technique. The difficulty of achieving longterm effective glucose control has encouraged us to develop a closed-loop control system, the artificial endocrine pancreas. PancreNo competing interests declared.