t isn’t unusual for people with diabetes to sometimes require corticosteroid treatment. Corticosteroids, or steroids for short, are used to reduce inflammation and suppress the immune system. They are often a last resort for a wide variety of conditions, in everything from asthma to allergy attacks to arthritis and ulcerative colitis. Steroids are also prescribed to prevent the immune system from seeing donated organs as foreign bodies and rejecting them after an organ transplant. One of the most commonly used steroids is prednisone.
“Among all medications available to treat different medical conditions, prednisone and similar steroids have the most profound effect on glucose metabolism. Medications such as prednisone can significantly increase glucose levels in patients with diabetes as well as individuals with impaired glucose tolerance or pre-diabetes,” says William Sullivan, M.D., a senior staff physician at Joslin Clinic in Boston and the Medical Director at the Joslin Clinic at Beth Israel Deaconess Hospital, Needham.
Prednisone is amazingly effective at calming inflamed tissue and reducing pain, but that comfort sometimes comes at a high price. Prednisone’s list of side effects is long and scary. The longer you are on the drug and the higher the dose, the more likely it is that you will experience side effects. When you have diabetes, even a short course of prednisone at a low dose is likely to wreak havoc with your blood glucose levels. In fact, another name for corticosteroids is glucocorticoids in honor of the powerful effect they have on glucose metabolism.
Prednisone induces elevated glucose levels by stimulating glucose secretion by the liver as well as reducing glucose transport into adipose and muscle cells. The overall effect is a reduction in glucose clearance. Elevated glucose levels can lead to glucose toxicity further impairing insulin secretion. Prednisone can also impair GLUT-2 expression. GlUT-2 is a protein mediated glucose transporter that ferries glucose across cell membranes. That means that people with diabetes taking prednisone are likely to see a significant bump in their blood glucose numbers depending on the dose of steroid given.
One of the most difficult things about taking prednisone is that it doesn’t elevate glucose readings consistently throughout the day. Prednisone taken in the morning usually doesn’t cause glucose levels to start to rise until lunch time. Blood glucose readings usually stay high through the early evening hours and then decline over night. Many people have normal or low glucose readings in the morning while taking prednisone.
This type of action curve can make it difficult to use flat basal insulin such as Lantus® or Levemir ®to treat people taking prednisone. Sometimes the use of NPH can be helpful for people on prednisone as it has a peak mid-afternoon and if given in the morning its effects taper off toward the evening, mirroring the action of the prednisone. When using NPH the overall effect is a better balance between your glucose levels and your insulin throughout the day.
The good news about prednisone is that it is cleared from the system fairly rapidly and once you stop taking it, blood glucose levels return to normal fairly rapidly.