Stopping smoking in 2010, is top of the list of New Year’s resolutions for many people.

But kicking the habit may come at a price that unexpectedly extends beyond the immediate cravings and bad temper, a new study suggests.

In the study, published in the Annals of Internal Medicine, adults who quit smoking experienced adverse changes in their metabolic profile and faced an increased risk of type 2 diabetes that peaked within 3 years - but was still observable 6 years - after quitting.

“Despite the well-established association of smoking with long-term diabetes risk, smoking cessation does not seem to reduce the short-term risk for diabetes but rather increases it. The increased risk may be explained by weight gain and systemic inflammation, “writes Dr Hsin-Chieh Yeh, of the Johns Hopkins University in Baltimore, USA.

Counselling patients about what to expect when they quit smoking, and close monitoring of   weight and glucose levels may improve the outcome, as could nicotine replacement therapy. Nicotine replacement not only reduces weight gain but may directly decrease systemic inflammation.

“Nicotine and its metabolites, through alpha-7 nicotinic acetylcholine receptors, may exert anti-inflammatory effects. These effects have been documented in leukocyte cells and adipocytes,” add the authors.

The researchers analysed data from the prospective cohort Atherosclerosis Risk in Communities (ARIC) Study of 10892 middle-aged adults who did not have diabetes at baseline, between 1987 and 1989.

Over 9 years of follow-up, 1,254 patients developed type 2 diabetes - a graded relationship existed between pack-years of smoking and incidence rates of type 2 diabetes. Diabetes incidence increased from 13.3 per 1,000 person-years in people who never smoked to 18.5 per 1000 person-years in the highest tertile of pack-years.

The risk of diabetes was increased by 40% among those in the highest tertile of smokers (more than 30 pack-years), compared with never-smokers.

The 380 patients in the study who quit smoking showed significant increases in weight, waist circumference and fasting glucose levels. They had an overall 73% greater risk of developing diabetes mellitus. Also, those who smoked more and gained the most weight had the highest short-term risk of developing diabetes.

The researchers conclude:  “Of course, smoking cessation has many beneficial health effects that outweigh this short-term risk. Nonetheless, physicians should be aware of this elevated risk and should consider countermeasures, especially for heavy smokers. Such countermeasures might include lifestyle counselling and aggressive weight management, and the use of nicotine replacement therapy.”

Reference:

Yeh HC, et al Ann Intern Med 2010; 152: 10-17.

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