Continuing Education Diabetes mellitus comprises a group of disorders characterized by persistent hyperglycemia, which affects some 15.7 million Americans. It is responsible for nearly 200,000 deaths annually and is the seventh leading cause of mortality in the United States. The cost of treating the disease exceeds $100 billion each year. Ninety percent of all patients with diabetes mellitus have Type 2 diabetes (noninsulin-dependent or adult onset), which results from defects in both insulin secretion and insulin sensitivity. Risk factors include a family histo- ry of Type 2 diabetes, obesity, a chronological age of 45 years or older, high total cholesterol levels or low levels of high-density lipoprotein (HDL) cholesterol, high triglyceride levels, race /ethnicity, hypertension, gestational diabetes, or delivery of very-large-weight babies (over 9 lb. at birth).
In healthy individuals, insulin helps to regulate the concentration of glucose in the bloodstream by promoting glucose cellular uptake. Patients with Type 2 diabetes suffer from insulin deficien- cy. It has been found that beta-cell dysfunction is present long before signs and symptoms of the disease are noticeable. Also, there is an inability for insulin secretion to compensate for insulin resistance. With insulin resistance, insulin's ability to promote glucose uptake by cells and suppress hepatic production is impaired. This may result in a decrease in the number or affinity of insulin receptors or a defect in the expression or translocation of the GLUT4 transporter protein. The onset of the signs and symptoms of Type 2 diabetes is often delayed because of a compensatory increase in pancreatic insulin secretion, which maintains normal plasma glucose levels. Type 2 diabetes becomes evident when pancreatic insulin secretion fails to compensate for insulin resistance because of beta-cell dysfunction or defects.
If left untreated or if the patient can't maintain adequate glucose control, the diabetic patient can develop long-term macrovascular and microvascular complications. Macrovascular complications include coronary artery disease (CAD), cerebrovascular disease (CVD), and peripheral vascular disease. Microvascular complications include neuropathy, retinopathy, and nephropathy. Typically, patients with Type 2 diabetes are obese and have high cholesterol levels and hypertension, which further increase their risks for macrovascular and microvascular complications.
Type 2 diabetes is often diagnosed by chance during a routine physical examination when urine glucose levels are high. Signs and symptoms include polyuria, polydipsia, weight loss, polyphagia, and, sometimes, blurred vision. The diagnostic criteria for Type 2 diabetes are listed in Table 1.
Glycemic control and complications. The treatment goals for Type 2 diabetes are listed in Table 2.
Current treatment goals are reflective of two major clinical trials that demonstrate the benefits of reducing glycosylated hemoglobin A^sub 1c^ (HbA^sub 1c^) levels to below 7%. The Diabetes Control & Complications Trial was able to demonstrate that tight glycemic control (insulin pump or multiple daily insulin injections with frequent monitoring) reduced the risk of diabetic retinopathy, nephropathy, and neuropathy by about 60% in patients with Type 1 diabetes. In the United Kingdom Prospective Diabetes Study (UKPDS), patients with Type 2 diabetes were recruited for a multicenter, randomized, prospective study. Patients were observed for an average of 10 years. The intent of the study was to determine whether intensive glycemic control with pharmacologic therapy can result in clinical benefits and whether the use of sulfonylureas (chlorpropamide, glyburide), metformin, or insulin has specific therapeutic advantages or disadvantages. Overall results demonstrated that patients who achieved and maintained HbA^sub 1c^, levels at or below 7% reduced the overall risk of retinopathy and nephropathy by 25% compared with conventional dietary measures. …