New study finds smoking increases risk of all forms of type-2 diabetes

At the 2025 European Association for the Study of Diabetes conference in Vienna, researchers presented findings showing that smoking significantly raises the risk of developing all four recognised subtypes of type-2 diabetes, those driven by insulin resistance, insulin deficiency, obesity, or age.

The effect was most pronounced in severe insulin-resistant diabetes (SIRD), considered one of the most aggressive forms, where smokers were more than twice as likely to be affected compared with non-smokers.

Risks observed among smokers:

Severe Insulin-Resistant Diabetes (SIRD): 2.15 times higher risk

Severe Insulin-Deficient Diabetes (SIDD): 20% higher risk

Mild Obesity-Related Diabetes (MOD): 29% higher risk

Mild Age-Related Diabetes (MARD): 27% higher risk

For heavy smokers defined as more than 15 pack-years (roughly a pack a day for 15 years), the risks increased further. In this group, the chance of developing SIRD was 2.35 times higher, while the likelihood of obesity-related diabetes rose by 57%, NDTV reported.

Smokeless tobacco also a risk

The research highlighted that smokeless tobacco carries dangers too. In Sweden, men who used snus, a moist oral tobacco, showed increased diabetes risk. While snus is rare in India, local products such as gutkha, khaini, and zarda are widely consumed and may have comparable health impacts.

The study further noted that heavy smokers with a genetic tendency toward weak insulin secretion were 3.5 times more likely to develop severe insulin-resistant diabetes (SIRD). This is particularly alarming for India, where genetic vulnerability to diabetes is already high.

Why it matters for India

India now has more than 100 million people living with diabetes, often at younger ages than in Western countries. Combined with the widespread use of both smoked and smokeless tobacco, the findings serve as a strong public health warning.

Key takeaways for prevention:

Quit smoking with the aid of nicotine replacement therapy or professional counselling.

Avoid smokeless tobacco — it is not a safer alternative.

Adopt healthy habits: stay physically active, eat fibre-rich foods, and maintain a healthy weight.

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