Diabetic smokers at risk for too-low blood sugar

NEW YORK (Reuters Health) - People with type 1 diabetes who smoke are more than twice as likely to have an episode of severe hypoglycemia, or very low blood sugar, as those who have never smoked, according to a new study.

Hypoglycemia can cause mental confusion, or even coma or seizures in severe instances. "Smoking, through its effect on hormone regulation and insulin clearance, has been hypothesized to result in severe hypoglycemia," Dr. Ronald Klein, of the University of Wisconsin-Madison, and colleagues write in the journal Diabetes Care.

To investigate this possibility, the researchers examined data on 537 people participating in the Wisconsin Epidemiologic Study of Diabetic Retinopathy.

Overall, 58 percent of the participants had never smoked, 27 percent were past smokers, and 15 percent were current smokers.

At least one episode of severe hypoglycemia -- involving loss of consciousness or overnight hospitalization -- was reported by 78 of the subjects, and the current smokers were more likely to have had an episode.

After taking account of other factors, smoking conferred a 2.6-fold increased risk of having severe hypoglycemia, Klein and colleagues report.

Furthermore, smoking was associated with similarly increased odds of having diabetes-related nerve damage, impaired kidney function, and sight-threatening retinal defects.

SOURCE: Diabetes Care, June 2007.