I have patients with low HDL and normal LDL whose HDL responds well to niacin. Some, however, develop mild glucose elevations of 100-110 mg/dL. Should the niacin be discontinued?
—Gerald L. Saliman, MD, Hillsborough, Calif.
This question raises several important points to consider: First, should these patients be treated at all? There are data to suggest that treating isolated hypoalphalipoproteinemia (low HDL) may reduce cardiovascular (CV) disease, but there is insufficient evidence to justify setting a specific goal value for HDL at this time (Am Heart J. 2004;147:966-976). Non-HDL targets should remain the primary end point of treatment. That said, most authorities would agree that in the presence of other CV risk factors, aggressive treatment of hypoalphalipoproteinemia is justified. Second, while niacin can worsen glycemic control in diabetic patients, it now appears that for most, this is of little significance. In fact, one study showed an improvement in hemoglobin A1c with the use of niacin (Pharmacotherapy. 2001;21:1473-1478). Thus, with vigilant glycemic monitoring, niacin can usually be safely prescribed for diabetic patients. The data in patients without diabetes is much less robust, and there is no clear answer to your question. However, a recent study showed that in women with impaired fasting glucose but fasting values <110 mg/dL, there was no significant increase in CV disease risk (Ann Intern Med. 2005;142:813-820). Given this, I would advise you to continue therapy (at least in women), monitor your patients closely, and consider discontinuing niacin if fasting glucose levels exceed 110.
—Daniel G. Tobin, MD (99-17)