Secondary diabetes occurs when the level of glucose, a type of sugar, in the blood is too high as the result of some other disease or condition. Normally, the pancreas secretes insulin in response to rising glucose levels, which causes cells to take glucose out of the blood. In type 2 diabetes, cells become less sensitive to this signal from insulin to take up glucose, a condition known as insulin resistance. Most secondary diabetes caused by medications involves an in increase insulin resistance, and in that sense it is similar to type 2 diabetes.
Glucocorticoids
Glucocorticoids are medications that are use to reduce inflammation. Frequently used glucocorticoids include solumedrol, prednisone and dexamethasone. They treat a variety of diseases, including rheumatoid arthritis, asthma and lupus. When used in large doses for extended periods of time, they can cause secondary diabetes. Glucocorticoids are similar to cortisol, a hormone secreted by the adrenal glands in response to stress. One of the stress-adapting functions of cortisol is an increase in blood glucose. Glucocorticoids cause diabetes both by this independent effect on blood glucose and by increasing insulin resistance.
Protease Inhibitors
Protease inhibitors, or PIs, are mostly used to treat infection with HIV, although they are occasionally used in patients with hepatitis C. Frequently used PIs include saquinavir, lopinavir and atazanavir. Some patients taking PIs develop diabetes, along with other disorders associated with insulin resistance, such as high cholesterol and high blood pressure. PIs have been shown to increase insulin resistance, although the process by which they do this is uncertain. One side effect of PIs is increased fat in the abdominal region, usually accompanied by decreased fat in the arms and legs. Since abdominal fat is known to decrease insulin sensitivity, it is not clear whether the additional fat in the abdomen or some separate side effect of the PIs is causing the insulin resistance.
Beta Blockers
Beta blockers are medications used to treat high blood pressure. Frequently used beta blockers include altenolol, carvedilol and metoprolol. Some studies, such as one published in the May 2008 issue of Diabetes Care, have shown an increased rate of diabetes among hypertensive patients treated with beta blockers as opposed to other blood pressure medicines. The issue is complicated, since type 2 diabetes and high blood pressure often occur together as part of a cluster of disorders related to insulin resistance knows as the metabolic syndrome. Because of their side effects, beta blockers are frequently used only in patients with more severe high blood pressure, who in many cases will also be those with a greater degree of insulin resistance.
References
- "Harrison's Principles of Internal Medicine"; Dennis L. Kasper
- "Principles of Pharmacology"; David E. Golan; 2005
- "Diabetes Care"; Determinants of New-onset Diabetes Among 19,257 Hypertensive Patients Randomized in the Anglo-Scandinavian Cardiac Outcomes Trial"; AK Gupta; May 2008
