Why smoking may increase heart risk

LOS ANGELES, June 15 (UPI) -- U.S. researchers suggest nicotine may be a reason smoking increases the risk of cardiovascular diseases.

Charles Drew University of Medicine and Science in Los Angeles and Western University of Health Sciences in Pomona, Calif., said the studies in animals found nicotine promotes insulin resistance -- a prediabetic condition where blood-sugar levels are above normal.

Other studies show people with prediabetes are at greater risk of developing stroke, heart attack and other cardiovascular diseases.

The researchers studied the effects of twice-daily injections of nicotine on 24 adult mice during a two-week period.

"Our results in mice show that nicotine administration leads to both weight loss and decreased food intake," study researcher Theodore Friedman of Charles Drew University said in a statement. "Mice exposed to nicotine have less fat. In spite of this, mice have abnormal glucose tolerance and are insulin resistant."

In the tests, the mice receiving nicotine also had high levels of the stress hormone cortisol, which increases blood pressure and blood sugar.

"Our results suggest that decreasing insulin resistance may reduce the heart disease seen in smokers," Friedman said.

The study was presented at The Endocrine Society's 91st annual meeting in Washington.