Smoking Raises Risk Of All Forms Of Type-2 Diabetes, New Study Finds

Smoking is already notorious for causing cancer and heart disease. Now, fresh research shows it also raises the risk of every form of type-2 diabetes.

A study presented at the European Association for the Study of Diabetes 2025 conference in Vienna found that smoking increases the likelihood of developing all four subtypes of type-2 diabetes, whether linked to insulin resistance, insulin deficiency, obesity or age.

The strongest impact was seen in severe insulin-resistant diabetes, one of the most aggressive subtypes. Smokers were more than twice as likely to develop SIRD as non-smokers.

Researchers from Sweden, Norway, and Finland analysed health data from over 7,000 people. Their findings:

• Severe Insulin-Resistant Diabetes: 2.15 times higher risk among smokers

• Severe Insulin-Deficient Diabetes: 20% higher risk

• Mild Obesity-Related Diabetes: 29% higher risk

• Mild Age-Related Diabetes: 27% higher risk

For heavy smokers with more than 15 pack-years (about a pack a day for 15 years), the risks jumped even further, with SIRD risk climbing 2.35 times and obesity-related diabetes risk rising 57%.

In Sweden, men who used snus, a smokeless tobacco product, also faced higher risks. While snus isn't common in India, homegrown products like gutkha, khaini, and zarda are widespread and may have similar effects.

The study also found that heavy smokers with a genetic predisposition to weak insulin secretion were 3.5 times more likely to develop SIRD. That’s especially concerning for Indians, who already carry strong genetic risk factors for diabetes.

India has over 100 million people living with diabetes, many at younger ages than in the West. With high tobacco use from both smoking and smokeless sources, the study is a wake-up call for public health.

Preventative measure include:

• Quit smoking with the help of nicotine replacement therapy or counselling.

• Avoid smokeless tobacco — it's not a safer alternative.

• Stay active, eat fibre-rich foods, and manage weight.

• Get screened early if you smoke or have a family history of diabetes.