A new study recently published in the journal The Lancet Diabetes & Endocrinology revealed that individuals with type 2 diabetes who stop smoking are likely to experience a worse glycemic control that can last up to three years. The study is entitled “The association between smoking cessation and glycaemic control in patients with type 2 diabetes: a THIN database cohort study” and was led by Dr. Deborah Lycett from Coventry University in the United Kingdom.
Smoking is known to increase the risk of developing type 2 diabetes and studies have suggested that this risk is even higher in the few years after quitting. It has been reported that diabetes control deteriorates temporarily, particularly in the first year after smoking cessation, and it can take 10 to 12 years for the risk of diabetes to become similar to the one of individuals who never smoked.
Researchers have now assessed whether quitting smoking is indeed linked to an altered diabetes control, how long this possible relation lasts and whether weight change and change in HbA1C (average measurement that indicates how well the body is controlling blood glucose levels) has any influence. The team conducted a retrospective study with data from 10,692 adult smokers with type 2 diabetes collected between 2005 and 2010 using UK primary care database The Health Improvement Network (THIN).
Researchers found that patients in this cohort who quit smoking and remained abstinent for at least one year (29%, 3,131 patients), had a significant increase of 2.3 mmol/mol (0.21%) in HbA1c one year after quitting before it gradually decreased as abstinence continued. Comparable levels to the ones of continual smokers were reached after 3 years. On the other hand, the 55% of the patients (5,831) that continued to smoke throughout the study had a more steady increase in HbA1C. The team also found that weight changes had no significant impact on the association between HbA1c levels and smoking cessation.
It has been previously shown that a HbA1c reduction by 1% (11mmol/mol) in a diabetes patient results in a 16% reduction in the likelihood of suffering heart failure and a 37% reduction in the likelihood of experiencing microvascular complications. This indicates the clinical relevance that small percentage changes in HbA1c levels have.
The team concluded that in type 2 diabetes patients, smoking cessation is linked to poorer glycemic control that can last up to three years. This poorer diabetes control is not associated with weight gain.
“Knowing that deterioration in blood glucose control occurs around the time of stopping smoking helps to prepare those with diabetes and their clinicians to be proactive in tightening their glycemic control during this time,” said Dr. Lycett in a news release. “Stopping smoking is crucial for preventing complications that lead to early death in those with diabetes. So people with diabetes should continue to make every effort to stop smoking, and at the same time they should expect to take extra care to keep their blood glucose well controlled and maximize the benefits of smoking cessation.”