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DIABETES MELLITUS

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ESSENTIALS OF DIAGNOSIS

Type 1 diabetes

  • Polyuria, polydipsia, and weight loss associated with random plasma glucose of 200 mg/dL (11.1 mmol/L) or more.

  • Plasma glucose of 126 mg/dL (7.0 mmol/L) or more after an overnight fast, documented on more than one occasion.

  • Ketonemia, ketonuria, or both.

  • Islet autoantibodies are frequently present.

Type 2 diabetes

  • Many patients are over 40 years of age and obese.

  • Polyuria and polydipsia. Ketonuria and weight loss generally are uncommon at time of diagnosis. Candidal vaginitis in women may be an initial manifestation. Many patients have few or no symptoms.

  • Plasma glucose of 126 mg/dL or more after an overnight fast on more than one occasion. Two hours after 75 g oral glucose, diagnostic values are 200 mg/dL (11.1 mmol) or more.

  • HbA1c 6.5% or more.

  • Hypertension, dyslipidemia, and atherosclerosis are often associated.

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Epidemiologic Considerations

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An estimated 29.1 million people (9.3%) in the United States have diabetes mellitus, of which approximately 1.25 million have type 1 diabetes and most of the rest have type 2 diabetes. A third group designated as “other specific types” by the American Diabetes Association (ADA) (Table 27–1) number only in the thousands. Among these are the rare monogenic defects of either B cell function or of insulin action, primary diseases of the exocrine pancreas, endocrinopathies, and medication-induced diabetes. Updated information about the prevalence of diabetes in the United States is available from the Centers for Disease Control and Prevention (http://www.cdc.gov/diabetes/pubs/estimates.htm#prev).

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Table Graphic Jump Location
Table 27–1.Other specific types of diabetes mellitus.
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Classification & Pathogenesis

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Diabetes mellitus is a syndrome with disordered metabolism and inappropriate hyperglycemia due to either a deficiency of insulin secretion or to a combination of insulin resistance and inadequate insulin secretion to compensate for the resistance.

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A. Type 1 Diabetes Mellitus
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This form of diabetes is due to pancreatic islet B cell destruction predominantly by an autoimmune process in over 95% of cases (type 1A) and idiopathic in less than 5% (type 1B). The rate of pancreatic B cell destruction is quite variable, being rapid in some individuals and slow in others. Type 1 diabetes is usually associated with ketosis in its untreated state. It occurs ...

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