-IBIS-1.7.6-
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endocrine system
diabetes mellitus
Diagnoses
definition and etiology
definition: A disease of carbohydrate metabolism due to a lack, or insufficient action, of circulating insulin thus causing hyperglycemia and known sequelae.
etiology: Diabetes mellitus (DM) is a leading cause of death in the U.S. and its incidence is rising. DM has been linked to the Western diet and lifestyle (particularly high carbohydrate intake). Other theoretical causes for the deficiency of insulin include viral infection of the beta cells, toxic reaction to N-nitroso compounds (found in smoked and cured meats), and auto-immune reaction.
DM is classically split into two types, insulin-dependent, called Type 1, and non-insulin-dependent, called Type 2. The two types vary markedly in etiology, pathophysiology, course and complications. Other types are also detailed:
insulin dependent Diabetes mellitus - IDDM (Type 1): These patients are susceptible to ketosis and have certain HLA antigens as well as pancreatic islet cell antibodies. Typically, this type of DM affects young people with peak occurrences at 5 years old and then again between 10 and 12 years old. It accounts for only about 10% of the diabetic patients in the U.S. Presentation is usually with ketoacidosis and history of recent weight loss.
Genetic susceptibility and a viral infection prompting immune targeting of pancreatic beta cells is a suggested mechanism for development of Type 1 DM. Recent research indicates that cows milk proteins may be an inciting antigen to trigger off autoantibodies to pancreatic cells.
(Maclaren N, Atkinson M. NEJM vol 327:5, July 30, 1992.)
non-insulin dependent Diabetes mellitus - NIDDM (Type 2): These diabetic patients are not susceptible to ketosis. Most are obese and between 50-70 years old at onset.
While the mechanism in Type 1 is the lack of insulin, in Type 2 the cause seems to be cellular resistance to available insulin.
DM from certain conditions: for example, pancreatic disease, malnutrition, etc.
gestational DM: glucose intolerance during pregnancy, whether present but unknown before pregnancy or developed post-conception.
impaired glucose tolerance (IGT): Patients who have blood results in-between the normal and diabetic reference ranges.
signs and symptoms
signs and symptoms:
Three Ps: polydipsia, polyuria, polyphagia.
Weight loss: marked in Type 1 and mild in Type 2. Many Type 2 diabetics do not manifest any weight loss.
Ketonuria in Type 1 diabetics.
Candida infections including monilia intertrigo, increased yeast vaginitis in women and balanitis in men.
signs and symptoms of common complications:
Neuropathy: bilateral, symmetric, distal (common in the feet); paresthesias; hyperthesias; and pain.
Atherosclerosis: e.g. heart attacks.
Microvascular disease: causing vision loss (DM is the leading cause of blindness in the U.S.) and kidney failure.
Diabetic foot ulcers.
lab findings:
Plamsa glucose greater than/equal to 200 mg/dl (11.1 mmol/dl) two hours after ingestion of 75g of anhydrous glucose dissolved in water.
Casual plasma glucose greater than or equal to 200 mg/dl (11.1 mmol/dl) in an individual with signs and symptoms of diabetes. Casual refers to a level any time of day without regard to meals. Signs and symptoms include polyphagia, polydipsia, polyphagia and unexplained weight loss.
Hypercholesterolemia and hypertriglyceridemia.
» in ketoacidosis:
increased plasma acetone
volume and electrolyte depletion
increased BUN and creatinine (creatinine unreliable because of increased acetone)
metabolic acidosis with pH << 7.25 and bicarbonate << 10 meq/l
increased WBC
serum amylase may be increased
hyperkalemia with insulin treatment
» in ketoacidosis:
increased plasma acetone
volume and electrolyte depletion
increased BUN and creatinine (creatinine unreliable because of increased acetone)
metabolic acidosis with pH < 7.25 and bicarbonate < 10 meq/l
increased WBC
serum amylase may be increased
hyperkalemia with insulin treatment
course and prognosis
DM patients are at risk for a number of problems (especially the younger patients who acquire IDDM): large vessel disease (early onset and increased severity of atherosclerosis); microvascular disease with thickening of the basal lamina (clinically important in the vessels of the eyes and kidneys); neuropathy (injury to peripheral nerves); and the possibility of falling into a hypoglycemic (insulin shock) or hyperglycemic (ketoacidosis coma) crisis. Despite insulin therapy, the morbidity for DM patients is high. Increased susceptibility to infection is common. Mortality and morbidity from pneumonia and influenza are increased.
differential diagnosis
renal glycosuria (This is generally a healthy individual found to have evidence of glucose on urine testing. Blood glucose is not elevated.)
Cushing's Syndrome
footnotes