A new study reveals why diabetic smokers suffer greater risk of complications such as nerve damage, blindness, and heart problems compared with non-diabetic smokers. For the first time, researchers have identified strong evidence that the nicotine in cigarettes raises blood sugar.

California State Polytechnic chemistry professor Xiao-Chuan Liu, Ph.D., who presented his research at an American Chemical Society meeting, said that up until now, no one knew what exact substance in cigarettes triggered a rise in blood sugar. Liu’s study, which used human blood samples, discovered that  as nicotine levels rise in the blood, so does the amount of HbA1c (blood glucose). HbA1c levels are a common indicator of the amount of blood sugar in the body. Liu found that nicotine raised HbA1c levels as much as 34 percent.

Liu says, “If you’re a smoker and have diabetes, you should be concerned and make every effort to quit smoking.” Should smokers with diabetes be worried about using nicotine-replacement products? The consensus is that the benefits of such products to help smokers stay off cigarettes outweighs the adverse effects of temporary elevations in blood sugar. Although experts caution against using them for extended periods of time.