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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 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.


An estimated 30.3 million people (9.4%) in the United States have diabetes mellitus, of which approximately 1.5 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 in the thousands. Among these are the 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 (

Table 27–1.Other specific types of diabetes mellitus.


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.

A. Type 1 Diabetes Mellitus

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. It occurs at any age but most commonly arises in children and young adults with a peak incidence before school age and ...

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