Diabetes Mellitus, Type 2

Diabetes mellitus is a chronic disease that requires long-term medical attention both to limit the development of its devastating complications and to manage them when they do occur. It is a disproportionately expensive disease; in 2002, the per-capita cost of healthcare was $13,243 for people with diabetes, while it was $2560 for those without diabetes.

This article focuses on the ED evaluation and treatment of the acute and chronic complications of diabetes other than those directly associated with hypoglycemia and severe metabolic disturbances such as diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). (Please see , , and for more information on these disorders.)

Pathophysiology

The 2 basic types of diabetes mellitus are type 1 and type 2. Type 1 diabetes mellitus is reviewed more fully in a separate eMedicine article (see).

Type 2 diabetes mellitus was once called adult-onset diabetes. Now, because of the epidemic of obesity and inactivity in children, type 2 diabetes mellitus is occurring at younger and younger ages. Although type 2 diabetes mellitus typically affects individuals older than 40 years, it has been diagnosed in children as young as 2 years of age who have a family history of diabetes.

Type 2 diabetes is characterized by peripheral insulin resistance with an insulin-secretory defect that varies in severity. For type 2 diabetes mellitus to develop, both defects must exist: all overweight individuals have insulin resistance, but only those with an inability to increase beta-cell production of insulin develop diabetes. In the progression from normal glucose tolerance to abnormal glucose tolerance, postprandial glucose levels first increase. Eventually, fasting hyperglycemia develops as inhibition of hepatic gluconeogenesis declines.

About 90% of patients who develop type 2 diabetes mellitus are obese. Because patients with type 2 diabetes mellitus retain the ability to secrete some endogenous insulin, those who are taking insulin generally do not develop DKA if it is stopped. Therefore, they are considered to require insulin but not to depend on insulin. Moreover, patients with type 2 diabetes mellitus often do not need treatment with oral antidiabetic medication or insulin if they lose weight or stop eating.

Maturity-onset diabetes of the young (MODY) is a form of type 2 diabetes mellitus that affects many generations in the same family with an onset in individuals younger than 25 years. Several types exist. Some of the genes responsible can be detected by using commercially available assays.

(GDM) is defined as any degree of glucose intolerance with onset or first recognition during pregnancy. GDM is a complication in approximately 4% of all pregnancies in the United States, though the rates may be 1-14% depending on the population studied. Untreated GDM can lead to fetal macrosomia, hypoglycemia, hypocalcemia, and hyperbilirubinemia. In addition, mothers with GDM have increased rates of cesarean delivery and chronic hypertension. To screen for GDM, a 50-g glucose screening test should be done at 24-28 weeks of gestation. This is followed by a 100-g, 3-hour oral glucose tolerance test if the patient's plasma glucose concentration at 1 hour after screening is greater than 140 mg/dL.