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Diabetes mellitus is a progressive disease that affects nearly 8% of the US population.1 Diabetes affects patients of all ages and is associated with chronic complications of microvascular, macrovascular, and neuropathic disorders. There are two major types of diabetes: type 1 (T1DM) and type 2 (T2DM). Other subclasses have been identified such as gestational diabetes (GDM) and secondary diabetes associated with hormonal syndromes, medications, diseases of the pancreas, and rare conditions involving insulin receptors.2 Diabetes is characterized by hyperglycemia due to defects in insulin action, insulin secretion or both. The key differences between T1DM and T2DM are the pathophysiology, etiology of hyperglycemia, and clinical presentation.

T1DM accounts for 5% to 10% of the patient population with diabetes. This cellular-mediated autoimmune process causes destruction of pancreatic β-cells resulting in an absolute deficiency of insulin. Due to the lack of insulin, glucose is not able to be used as energy. The onset of symptoms leading to the diagnosis of T1DM is abrupt in nature occurring within days to weeks. Most often, patients will present with the classic symptoms of polydipsia, polyuria, polyphagia, and weight loss or ketoacidosis due to lipolysis.2-5

T2DM is more prevalent in adult populations. Nevertheless, new cases diagnosed at a younger age are occurring at epidemicproportions due to lack of physical activity and obesity in the western culture. Unlike patients with T1DM, patients with T2DM do not necessarily need initial insulin treatment in order to survive. Patients with T2DM have impaired insulin secretion as well as insulin resistance at sites such as the liver, muscles, and adipocytes. Patients with T2DM are able to produce insulin, but the amount may not be sufficient to keep up with the body's glucose metabolism, or the insulin that is produced by a patient with T2DM may not work appropriately at its receptor sites.

It is recommended that pregnant and all overweight adults and children who are at risk for diabetes be screened for diabetes (Table 58-1).2 Screening efforts are used to identify patients who are likely to develop or have diabetes. The American Diabetes Association (ADA) does not recommend obtaining fasting plasma glucose levels as a measure of screening every patient. It is recommended to have patients fill out the ADA Diabetes Risk Screening Tests first and, if a patient scores a 10 or greater on this test, a finger stick blood sample would be appropriate. The online version of this screening tool is available at The diagnosis of diabetes or classification of prediabetes can be obtained by a laboratory measurement of a hemoglobin A1c, fasting plasma glucose level, or with the administration of an oral glucose tolerance test (OGTT) followed by a plasma glucose level (Table 58-2).2 Once diagnosed with diabetes, clinicians can use the A1c to explain to patients their long-standing glucose control over the last 2 to 3 months by expressing the A1c into the ...

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