Quitting smoking can temporarily worsen diabetes control

The Lancet: It is recommended for type 2 diabetics to quit smoking as soon as possible to reduce their cardiovascular risk already high in relation to diabetes. Smoking cessation may yet have a temporary adverse effect on glycemic control. This is the conclusion of a British study that was published in the journal "The Lancet Diabetes & Endocrinology." Coventry University researchers analyzed over a period of 6 years of data, 10,692 smoking adults with type 2 diabetes. During the study, 29% of participants (3,131 people) have stopped smoking for at least one year.

Among former smokers, the team found an increase of 0.21% of HbA1c on smoking cessation. The rate, however, decreased gradually with the maintenance of smoking cessation. Weight changes had no connection with fluctuations of diabetes control.
According to the authors, a reduction in HbA1c of one per cent causes a 16% decrease in the risk of heart failure  and reduces by 37% the risk of microvascular complications in diabetics. This clearly shows how even small changes can be significant.