Increased risk of LADA in people who smoke or use smokeless tobacco

Previous studies have shown that smokers have an increased risk of developing type 2-diabetes. However, research shows that being exposed to smoking in the fetal stage seems to have a protective effect against type 1-diabetes. But if and how it affects the risk of developing LADA, the autoimmune form of diabetes remains unclear.  

The purpose of the study was to investigate if tobacco use and genetic susceptibility interact and influence the risk of developing LADA. By using questionnaires and genetic analyses the authors have investigated the connection between smoking and the risk of LADA. 

The participants answered a questionnaire with questions about their smoking habits. The base of the study are the questions together with clinical analyzes from ANDIS-register (All New Diabetics in Scania) and the Norwegian HUNT-Study. 

The results show that smokers or smokeless tobacco users have an increased risk of developing LADA. Previous smokers had a lower risk compared to current smokers. For people who smoked and had increased genetic susceptibility for autoimmunity, there was a higher risk compared to people that did not have genetic susceptibility. For smokers, the risk of LADA was two-fold compared with people who never smoked. 

Previous studies have shown that nicotine influence insulin sensitivity which suggests that smoking increases the risk by affecting the insulin resistance rather than the autoimmune process of LADA. Another explanation could be that Insulin speeds up the development of diabetes in people with a certain genotype due to their immune system being more likely to be affected by environmental factors such as smoking.