Researchers uncover first hard evidence that nicotine raises blood sugar levels in individuals with type 1 diabetes and type 2 diabetes

For years, health experts have known that there was an association between smoking and poor blood sugar control in individuals with type 1 diabetes or type 2 diabetes. However, they lacked the hard evidence to show that any substance in cigarette smoke actually caused unhealthy blood sugar levels.

Doctors now have that proof, after a team of researchers from the California Polytechnic University found that nicotine directly causes increases in HbA1c levels, an important measure of blood sugar control over time.

The team reported at the 241st National Meeting & Exposition of the American Chemical Society that their tests showed concentrations of nicotine on the order of what is generally found in smokers causes HbA1c levels to rise.

The findings are important, the researchers said, because it has long been speculated that some component of cigarette smoke likely causes blood sugar to rise. However, the lack of hard evidence made it difficult for doctors to confidently recommend to their diabetic patients to give up the habit. The results of the study provide conclusive evidence of the direct relationship between smoking and blood sugar levels.

Individuals with type 1 diabetes or type 2 diabetes who have poor control of their blood sugar are more likely to experience complications, such as heart disease, kidney failure, nerve damage and retinopathy. However, the researchers said that their findings show quitting smoking can be a major step toward improving blood sugar levels.

"This is an important study," said Xiao-Chuan Liu, who led the study. "It is the first study to establish a strong link between nicotine and diabetes complications. If you're a smoker and have diabetes, you should be concerned and make every effort to quit smoking."