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For further information, see CMDT Part 27-01: Diabetes Mellitus
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Essentials of Diagnosis
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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
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General Considerations
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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
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Often asymptomatic
Polyuria
Increased thirst (polydipsia)
Weakness or fatigue
Recurrent blurred vision
Chronic skin infections
Hyperglycemic hyperosmolar coma
Serum osmolality exceeds 320–330 mOsm/L
Patients are profoundly dehydrated, hypotensive, lethargic, or comatose but without the Kussmaul respirations of ketoacidosis
Vulvovaginitis or anogenital pruritus or balanoposthitis
Peripheral neuropathy
Obesity
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Differential Diagnosis
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Endocrinopathies
Type 1 diabetes mellitus
Cushing syndrome
Acromegaly
Pheochromocytoma
Glucagonoma
Somatostatinoma
Drugs
Pancreatic insufficiency
Other
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Nondiabetic glycosuria (benign)
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Genetic
Fanconi syndrome
Chronic kidney disease
Pregnancy
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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
Lipoprotein abnormalities in obese persons with type 2 diabetes include