Diabetes mellitus is a metabolic disorder characterized by hyperglycemia and results from defective insulin production, secretion, or utilization.
Pathophysiology and Etiology
There is an absolute or relative lack of insulin produced by the beta cell, resulting in hyperglycemia.
Defects at the cell level, impaired secretory response of insulin to rises in glucose, and increased nocturnal hepatic glucose production (gluconeogenesis) are seen in type 2 diabetes.
Etiology of type 1 diabetes is not well understood; viral, autoimmune, and environmental theories are under review.
Etiology of type 2 diabetes involves heredity, genetics, and obesity
Type 1 Diabetes Mellitus
Type 1 diabetes mellitus was formerly known as insulin dependent diabetes mellitus and juvenile diabetes mellitus.
Little or no endogenous insulin, requiring injections of insulin to control diabetes and prevent ketoacidosis.
Five to 10% of all diabetic patients have type 1.
Etiology: autoimmunity, viral, and certain histocompatibility antigens as well as a genetic component.
Usual presentation is rapid with classic symptoms of polydipsia, polyphagia, polyuria, and weight loss.
Most commonly seen in patients under age 30 but can be seen in older adults.
Type 2 Diabetes Mellitus
Type 2 diabetes mellitus was formerly known as noninsulin dependent diabetes mellitus or adult onset diabetes mellitus.
Caused by a combination of insulin resistance and relative insulin deficiency- some individuals have predominantly insulin resistance, whereas others have predominantly deficient insulin secretion, with little insulin resistance.
Approximately 90% of diabetic patients have type 2.
Etiology: strong hereditary component, commonly associated with obesity.
Usual presentation is slow and typically insidious with symptoms of fatigue, weight gain, poor wound healing, and recurrent infection.
Found primarily in adults over age 30; however, may be seen in younger adults and adolescents who are overweight.
Patients with this type of diabetes, but who eventually may be treated with insulin, are still referred to as having type 2 diabetes.
Prediabetes
Prediabetes is an abnormality in glucose values intermediate between normal and overt diabetes.
Impaired Fasting Glucose
A new category adopted by the American Diabetes Association in 1997 and redefined in 2004.
Occurs when fasting blood glucose is greater than or equal to 100 but less than 126 mg/dL.
Impaired Glucose Tolerance
Defined as blood glucose measurement on a glucose tolerance test greater than or equal to 140 mg/dl but less than 200 in the 2-hour sample.
Asymptomatic; it can progress to type 2 diabetes or remain unchanged.
May be a risk factor for the development of hypertension, coronary heart disease, and hyperlipidemias.
Gestational Diabetes Mellitus
Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance occurring during pregnancy.
Occurs in approximately 4% of pregnancies and usually disappears after delivery.
Women with GDM are at higher risk for diabetes at a later date.
GDM is associated with increased risk of fetal morbidity.
Screening for GDM for all pregnant women other than those at lowest risk (under age 25, of normal body weight, have no family history of diabetes, are not a member of an ethnic group with high prevalence of diabetes) should occur between the 24th and 28th weeks of gestation.
Diabetes Associated with Other Conditions
Certain drugs can decrease insulin activity resulting in hyperglycemia- corticosteroids, thiazide diuretics, estrogen, phenytoin.
Disease states affecting the pancreas or insulin receptors- pancreatitis, cancer of the pancreas, Cushing's disease or syndrome, acromegaly, pheochromocytoma, muscular dystrophy, Huntington's chorea.
Pathophysiology and Etiology
There is an absolute or relative lack of insulin produced by the beta cell, resulting in hyperglycemia.
Defects at the cell level, impaired secretory response of insulin to rises in glucose, and increased nocturnal hepatic glucose production (gluconeogenesis) are seen in type 2 diabetes.
Etiology of type 1 diabetes is not well understood; viral, autoimmune, and environmental theories are under review.
Etiology of type 2 diabetes involves heredity, genetics, and obesity
Type 1 Diabetes Mellitus
Type 1 diabetes mellitus was formerly known as insulin dependent diabetes mellitus and juvenile diabetes mellitus.
Little or no endogenous insulin, requiring injections of insulin to control diabetes and prevent ketoacidosis.
Five to 10% of all diabetic patients have type 1.
Etiology: autoimmunity, viral, and certain histocompatibility antigens as well as a genetic component.
Usual presentation is rapid with classic symptoms of polydipsia, polyphagia, polyuria, and weight loss.
Most commonly seen in patients under age 30 but can be seen in older adults.
Type 2 Diabetes Mellitus
Type 2 diabetes mellitus was formerly known as noninsulin dependent diabetes mellitus or adult onset diabetes mellitus.
Caused by a combination of insulin resistance and relative insulin deficiency- some individuals have predominantly insulin resistance, whereas others have predominantly deficient insulin secretion, with little insulin resistance.
Approximately 90% of diabetic patients have type 2.
Etiology: strong hereditary component, commonly associated with obesity.
Usual presentation is slow and typically insidious with symptoms of fatigue, weight gain, poor wound healing, and recurrent infection.
Found primarily in adults over age 30; however, may be seen in younger adults and adolescents who are overweight.
Patients with this type of diabetes, but who eventually may be treated with insulin, are still referred to as having type 2 diabetes.
Prediabetes
Prediabetes is an abnormality in glucose values intermediate between normal and overt diabetes.
Impaired Fasting Glucose
A new category adopted by the American Diabetes Association in 1997 and redefined in 2004.
Occurs when fasting blood glucose is greater than or equal to 100 but less than 126 mg/dL.
Impaired Glucose Tolerance
Defined as blood glucose measurement on a glucose tolerance test greater than or equal to 140 mg/dl but less than 200 in the 2-hour sample.
Asymptomatic; it can progress to type 2 diabetes or remain unchanged.
May be a risk factor for the development of hypertension, coronary heart disease, and hyperlipidemias.
Gestational Diabetes Mellitus
Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance occurring during pregnancy.
Occurs in approximately 4% of pregnancies and usually disappears after delivery.
Women with GDM are at higher risk for diabetes at a later date.
GDM is associated with increased risk of fetal morbidity.
Screening for GDM for all pregnant women other than those at lowest risk (under age 25, of normal body weight, have no family history of diabetes, are not a member of an ethnic group with high prevalence of diabetes) should occur between the 24th and 28th weeks of gestation.
Diabetes Associated with Other Conditions
Certain drugs can decrease insulin activity resulting in hyperglycemia- corticosteroids, thiazide diuretics, estrogen, phenytoin.
Disease states affecting the pancreas or insulin receptors- pancreatitis, cancer of the pancreas, Cushing's disease or syndrome, acromegaly, pheochromocytoma, muscular dystrophy, Huntington's chorea.
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