Diabetes Mellitus

Diabetes Mellitus

Is a multisystem disease related to abnormal insulin production, impaired insulin utilization, or both. Diabetes Mellitus is a serious health problem throughout the world. It is the 5th leading cause of death in the U.S. It is the leading cause of heart disease, stroke, adult blindness, and nontraumatic lower limb amputations.

Etiology and Pathophysiology

Current theories link the cause of diabetes, singly or in combination, to genetic, autoimmune, viral, and environmental factors (obesity, stress). Regardless of its cause, diabetes is primarily a disorder of glucose metabolism related to absent or insufficient insulin supplies and/or poor utilization of the insulin that is available. The two most common types of diabetes are classified as type I or type II diabetes mellitus. Gestational diabetes and secondary diabetes are other classifications of diabetes commonly seen in clinical practice

Normal Insulin Metabolism

Insulin is a hormone produced by the B cells in the islets of Langerhans of the pancreas. Under normal conditions, insulin is continuously released into the bloodstream in small pulsatile increments (a basal rate), with increased release (bolus) when food is ingested. The activity of released insulin lowers blood glucose and facilitates a stable, normal glucose range of approximately 70 to 120 mg/dl. The average amount of insulin secreted daily by and adult is approx. 40 to 50 U, or 0.6 U/kg of body weight.

Other hormones (glucagons, epinephrine, growth hormone, and cortisol) work to oppose the effects of insulin and are often referred to as counterregulatory hormones. These hormones work to increase blood glucose levels by stimulating glucose production and output by the liver and by decreasing the movement of glucose into the cells. Insulin and the these counterregulatory hormones provide a sustained but regulated release of glucose for energy during food intake and periods of fasting and usually maintain blood glucose levels within the normal range. An abnormal production of any or all of these hormones may be present in diabetes.

Insulin is released from the pancreatic B cells as its precursor, proinsulin, and is then routed through the liver. Proinsulin is composed of two polypeptide chains, chain A and chain B, which are linked by the C-peptide chain. The presence of C peptide in serum and urine is a useful indic...

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Pancreas Transplantation

Is used as a tx option for patients with type I diabetes mellitus who have end-stage renal disease and who have had or plan to have a kidney transplant. Kidney and pancreas transplants are often done together. If renal failure is not present, the ADA recommends that pancreas transplantation should only be considered for patients who exhibit the following three criteria:

*A history of frequent, acute, and severe metabolic complications (hypoglycemia, hyperglycemia, ketoacidosis) requiring medical attention

*Clinical and emotional problems with exogenous insulin therapy that are so severe as to be incapacitating

*Consistent failure of insulin-based management to prevent acute complications

Successful pancreas transplantation can improve the quality of life of people with diabetes, primarily by eliminating the need for exogenous insulin, frequent daily blood glucose measurements and many of the dietary restrictions imposed by the disorder. Pts who undergo pancreas transplantation require immunosuppression to prevent rejection of the graft and potential recurrence of the autoimmune process that might again destroy pancreatic islet cells.