Smoking harms kidney function in type 2 diabetics

Smokers who also suffer from type 2 diabetes are more than twice as likely to have impaired kidney function as compared to non-smokers. Researchers from the University of Foggia in Italy found that it is important that diabetics should quit smoking. While smoking is known to damage the kidneys of individuals with type 1 diabetes, its effects have not been studied as extensively in people with type 2 diabetes. To investigate, the researchers looked at a measure of kidney function called glomerular filtration rate (GFR) in 158 smokers and 158 never-smokers, all of whom had type 2 diabetes. GFR measures how quickly the tiny blood vessels in the kidneys are able to filter waste products out of the blood. Twelve percent of the non-smokers had a low GFR, as compared to 21 percent of the smokers, making smokers 2.2 times more likely to have impaired kidney function. The effects were strongest in those who had had diabetes for the shortest time; in this group, smokers were more than four times as likely as non-smokers to have low GFR, indicating impaired kidney function. The researchers also found higher levels of tissue-damaging byproducts of metabolism known as oxygen free radicals in the smokers, which they suggest might have helped fuel the damage. While waiting for prospective studies to clarify the relationship between smoking and kidney damage in diabetic patients, efforts to help type 2 diabetic patients to quit smoking are strongly recommended.