Diabetes mellitus is a metabolic disorder characterized by hyperglycemia resulting from lack of insulin, lack of insulin effect, or both. Three general classifications are recognized:
· type 1—absolute insulin insufficiency
· type 2—insulin resistance with varying degrees of insulin secretory defects
· gestational diabetes—manifested during pregnancy.
Age Alert
Although possible at any age, type 1 usually manifests before age 30. It requires exogenous insulin and dietary management.
Type 2 usually occurs in obese adults after age 40. It's treated with diet and exercise combined with various antidiabetic drugs; treatment may include insulin therapy.
Causes
· Heredity
· Environment (infection, toxins)
· Stress, diet, lack of exercise in genetically susceptible persons
· Pregnancy
Pathophysiology
Type 1 and type 2 diabetes mellitus are two separate and distinct pathophysiological entities. In persons genetically susceptible to type 1 diabetes, a triggering event, possibly a viral infection, causes production of autoantibodies which kill the beta cells of the pancreas. This leads to a decline in and an ultimate lack of insulin secretion. Insulin deficiency, when more than 90% of the beta cells have been destroyed, leads to hyperglycemia, enhanced lipolysis, and protein catabolism.
Type 2 diabetes mellitus is a chronic disease caused by one or more of the following factors: impaired insulin production, inappropriate hepatic glucose production, or peripheral insulin receptor insensitivity.
Gestational diabetes mellitus is glucose intolerance during pregnancy in a woman not previously diagnosed with diabetes. This may occur if placental hormones counteract insulin, causing insulin resistance.
Signs and symptoms
· Polyuria and polydipsia
· Nausea; anorexia (common) or polyphagia (occasional)
· Weight loss (usually 10% to 30%; persons with type 1 diabetes often have almost no body fat at diagnosis)
· Headaches, fatigue, lethargy, reduced energy levels, impaired school or work performance
· Muscle cramps, irritability, emotional lability
· Vision changes such as blurring
· Numbness and tingling
· Abdominal discomfort and pain; diarrhea or constipation
· Recurrent vaginal candidiasis
Diagnostic test results
In men and nonpregnant women
· Two of the following criteria obtained more than 24 hours apart, using the same test twice or any combination are indicators of the disease:
§ fasting plasma glucose level of 126 mg/dl or more on at least two occasions
§ typical symptoms of uncontrolled diabetes and random blood glucose level of 200 mg/dl or more
§ blood glucose level of 200 mg/dl or more 2 hours after ingesting 75 g of oral dextrose.
· Other criteria include:
§ diabetic retinopathy on ophthalmologic examination
§ other diagnostic and monitoring tests, including urinalysis for acetone and glycosylated hemoglobin (reflects glycemic control over the past 2 to 3 months).
In pregnant women
· Positive glucose tolerance test reveals high peak blood sugar levels after ingestion of glucose (1 g/kg body weight) and delayed return to fasting levels.
Treatment
Type 1 diabetes mellitus
· Insulin replacement, meal planning, and exercise (current forms of insulin replacement include mixed-dose, split mixed-dose, and multiple daily injection regimens and continuous subcutaneous insulin infusions)
· Pancreas transplantation (currently requires chronic immunosuppression)
Type 2 diabetes mellitus
· Oral antidiabetic drugs to stimulate endogenous insulin production, increase insulin sensitivity at the cellular level, suppress hepatic gluconeogenesis, and delay GI absorption of carbohydrates (drug combinations may be used)
· Exogenous insulin, alone or with oral antidiabetic drugs, to optimize glycemic control
Type 1 and type 2 diabetes mellitus
· Individualized meal plan designed to meet nutritional needs, control blood glucose and lipid levels, and reach and maintain appropriate body weight
· Weight reduction (obese patient with type 2 diabetes mellitus) or high calorie allotment, depending on growth stage and activity level (type 1 diabetes mellitus)
Gestational diabetes
· Medical nutrition therapy and exercise
· Alpha glucosidase inhibitors, injected insulin, or both (if euglycemia not achieved)
· Counseling on the high risk for gestational diabetes in subsequent pregnancies and type 2 diabetes later in life
· Exercise and weight control to help avert type 2 diabetes
Clinical Tip
Although patients with type 2 diabetes are able to suppress development of ketones under basal conditions, they may develop diabetic ketoacidosis in the presence of precipitating factors such as sepsis.
P.281
TYPE 1 AND TYPE 2 DIABETES MELLITUS
|
|
|
|
