High blood sugar levels are the distinguishing feature of diabetes mellitus. The two types of diabetes are differentiated by the underlying problem. People with type 1 diabetes produce little to no insulin--the hormone that controls blood glucose (sugar) levels. In people with type 2 diabetes, the problem is insulin resistance--lack of responsiveness to the insulin produced. Diabetes drug therapy is tailored based on the type of diabetes, response to therapy and maintaining good blood sugar control.
Therapeutic Insulins
Therapeutic insulins replace the insulin the body has failed to produce. These medications are the mainstay of therapy for type 1 diabetes, and may be used in type 2 diabetics who have insufficient insulin production. Several insulins are available; they differ in terms of the how quickly they take effect, when the maximum circulating dose is reached, and how long they remain active. Premixed combinations of different acting insulins are available.
Rapid or fast-acting insulins (insulin lispro, insulin aspart and insulin glulisine) begin to act within 15 minutes of injection. Activity peaks at 30 to 90 minutes and lasts for 3 to 5 hours. Regular insulin is short acting; it begins to work 30 to 60 minutes after injection. The peak activity occurs at 2 to 4 hours, and the total duration of action is 5 to 8 hours. Intermediate-acting insulins (NPH, insulin isophane, insulin lispro protamine and insulin aspart protamine) begin working 1 to 3 hours after injection. Peak activity occurs at roughly 8 hours; total duration of action is 12 to 18 hours. Long-acting insulins (insulin detemir and insulin glargine) begin working approximately 60 minutes after injection. There is no peak in activity; these drugs remain active for 20 to 26 hours.
Metformin
Metformin is an oral medication for type 2 diabetes; it reduces blood glucose by decreasing liver glucose production and release. The liver is the body's glucose manufacturer and warehouse. When the body has more glucose than it needs, the liver stores it for future use. When glucose is needed, the liver responds by releasing glucose from storage or manufacturing it from other chemicals. Metformin blocks both the release and production of sugar. It also reduces glucose absorption from the gut and augments the insulin sensitivity of the body's cells. Metformin is often the drug of choice for people newly diagnosed with type 2 diabetes.
Sulfonylureas
Sulfonylureas stimulate production of insulin by the pancreas; this oral medication is used only for type 2 diabetes. Drugs in this group of diabetes medicines include glipizide (regular and long-acting), glyburide, glimepiride, chlorpropamide, tolazamide and tolbutamide. Sulfonylureas may be used alone or in combination with other diabetes medicines. A possible side effect of the sulfonylureas is weight gain. This is a particularly undesirable side effect as many people with type 2 diabetes are overweight or obese; additional weight gain may further aggravate insulin resistance. Hypoglycemia (low blood sugar) is also a possible side effect of the sulfonylureas.
Thiazolidinediones
Thiazolidinediones act to counter the insulin resistance of type 2 diabetes by improving sensitivity to insulin, especially in muscle, fat and liver tissue. The drugs in this group include pioglitazone and rosiglitazone. Thiazolidinediones can be used alone or in combination with other diabetes medicines. Weight gain is a common side effect of these drugs. Both pioglitazone and rosiglitazone carry warnings regarding possible risk for new or worsening heart failure associated with use of these medications.
References
- Merck Manual: Diabetes Mellitus, Treatment
- American Diabetes Association: Medication, Insulin
- American Diabetes Association: Medication, Oral Medication
- Mayo Clinic: Diabetes Treatment, Medications for Type 2 Diabetes
- National Institute of Diabetes and Digestive and Kidney Diseases: What I Need to Know about Diabetes Medicines
