Niacin, the B vitamin which is known to raise blood glucose levels when consumed in large quantities - making it inappropriate for use as a diabetes treatment - could in fact be effective in treating the disease, provided the dosage is small enough.
This is the claim of researchers from the University of Texas Southwestern Medical Center, who carried out a trial of extended release niacin under the Niaspan brand, produced by Kos Pharmaceuticals. The findings of the trial are reported in this week's Archives of Internal Medicine.
The 148 participants in the trial showed a significant improvement in lipid levels and minimal changes in glycemic control following medication with Niaspan.
"Previous reports have shown that niacin in high doses raises blood glucose, but this trial shows that in doses of 1,000 milligrams per day and 1,500 mg/d, niacin therapy was well-tolerated and changes in glycemic control were minimal," said Dr Scott Grundy, the study's lead author. "Low doses of an extended form of niacin also had favourable effects on blood lipids and lipoproteins."
The researchers targeted niacin therapy for a condition in patients with diabetes called dyslipidemia, which is characterised by high levels of triglycerides and other lipid-related abnormalities along with depressed levels of the healthier high-density lipoprotein (HDL) cholesterol.
"Niacin therapy has been discouraged by clinicians because high doses can worsen glycemic control in patients with diabetes," said Dr Gloria Vega, a professor of clinical nutrition and a study co-author. "In this study we evaluated the tolerance and effectiveness of niacin at low doses. This extended-release form is designed to circumvent the bothersome side effects of regular niacin, such as flushing of the skin."
During the trial, the study participants were divided into three groups. They received either 1,500 mg/d of extended-release niacin, 1,000 mg/d of extended-release niacin or a placebo. About half of the study participants continued taking their prescribed statin drugs for cholesterol lowering during the trial, and 81 per cent continued their medications for diabetes.
In the 1,500 mg/d group, HDL increased as much as 24 per cent, triglycerides decreased as much as 36 per cent, and the 'bad' cholesterol, low-density lipoproteins (LDL), decreased by 7 per cent. In the 1,000 mg/d group HDL increased by 19 per cent.
Patients with diabetic dyslipipdemia are commonly treated with triglyceride-lowering drugs known as fibrates, but niacin is more effective for raising HDL, the researchers said. "Niacin clearly increases HDL cholesterol and reduces triglycerides in individuals with type 2 diabetes," Vega said.
"Most patients with diabetes will require lipid-lowering therapy," Grundy said. "The use of statins to lower LDL cholesterol is becoming routine therapy for the majority of patients; however, this study indicates that the addition of niacin to statin therapy will provide additional benefit for improvement of blood lipids and lipoproteins in patients with diabetes."