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Key Features

Essentials of Diagnosis

  • Typically > 40 years of age

  • Obesity

  • Polyuria and polydipsia

  • Candidal vaginitis sometimes an initial manifestation

  • Often few or no symptoms

  • After an overnight fast, plasma glucose ≥ 126 mg/dL (7 mmol/L) more than once

  • After 75 g oral glucose, diagnostic values are ≥ 200 mg/dL (11.1 mmol/L) 2 h after the oral glucose

  • Hemoglobin A1c (HbA1c) ≥ 6.5%

  • Often associated with hypertension, dyslipidemia, and atherosclerosis

General Considerations

  • Circulating endogenous insulin is sufficient to prevent ketoacidosis but inadequate to prevent hyperglycemia from tissue insensitivity

  • Strong genetic influences

  • Prevalence of obesity in type 2 diabetes mellitus

    • 30% in Chinese and Japanese

    • 60–70% in North Americans, Europeans, and Africans

    • Nearly 100% in Pima Indians and Pacific Islanders from Nauru or Samoa

  • Abdominal fat, with an abnormally high waist–hip ratio, is generally associated with obesity in type 2 diabetes. This visceral obesity correlates with insulin resistance, whereas subcutaneous fat seems to have less of an association

Demographics

  • ~28 million Americans have type 2 diabetes

  • Traditionally occurred in middle-aged adults but now more frequently encountered in children and adolescents

  • No gender predominance

Clinical Findings

Symptoms and Signs

  • Polyuria

  • Increased thirst (polydipsia)

  • Weakness or fatigue

  • Recurrent blurred vision

  • Vulvovaginitis or anogenital pruritus or balanoposthitis

  • Peripheral neuropathy

  • Obesity

  • Often asymptomatic

Differential Diagnosis

Hyperglycemia

  • Endocrinopathies

    • Type 1 diabetes mellitus

    • Cushing syndrome

    • Acromegaly

    • Pheochromocytoma

    • Glucagonoma

    • Somatostatinoma

  • Drugs

    • High-dose corticosteroids

    • Thiazides

    • Phenytoin

    • Niacin

    • Oral contraceptives

    • Pentamidine

  • Pancreatic insufficiency

    • Subtotal pancreatectomy

    • Chronic pancreatitis

    • Hemochromatosis ("bronze diabetes")

    • Hemosiderosis

  • Other

    • Gestational diabetes

    • Cirrhosis

    • Schmidt syndrome (polyglandular failure: Addison disease, autoimmune thyroiditis, diabetes)

Polyuria

  • Diabetes insipidus

Hypercalcemia

  • Psychogenic polydipsia

Nondiabetic glycosuria (benign)

  • Genetic

  • Fanconi syndrome

  • Chronic kidney disease

  • Pregnancy

Diagnosis

Laboratory Tests

  • Fasting plasma glucose ≥ 126 mg/dL (7 mmol/L) or ≥ 200 mg/dL (11.1 mmol/L) 2 h after glucose load (Table 27–4)

  • HbA1c of at least 6.5%

  • Urine glucose (Clinistix, Diastix)

  • Ketonuria on occasion without ketonemia (Acetest, Ketostix)

  • HbA1c reflects glycemic control over preceding 8–12 weeks

  • Serum fructosamine

    • Reflects glycemic control over preceding 2 weeks

    • Helpful in the presence of abnormal hemoglobins and in ascertaining glycemic control at time of conception among diabetic women

  • Lipoprotein abnormalities in obese persons with type 2 diabetes include

    • High serum triglyceride (300–400 mg/dL)

    • Low high-density lipoprotein (HDL) cholesterol (< 30 mg/dL)

    • A qualitative change in low-density lipoprotein (LDL) particles

  • These abnormalities differ from type 1 diabetes, which is associated with only slight elevation of LDL cholesterol and serum triglycerides and minimal change in HDL cholesterol

Treatment

Medications

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