Caffeine may increase susceptibility to type-2 diabetes, the most common form of diabetes in Canada, new research suggests.

Obesity and inactivity are the two biggest risk factors for type-2 diabetes. Nutritional scientists believe these factors may also be linked to diets high in caffeine.

A three-year study is looking into the link between caffeine use and type-2 diabetes. Terry Graham, a Human Biology and Nutritional Sciences researcher at the University of Guelph is part of a tri-university effort.

Caffeine can have an unhealthy affect on insulin levels
Caffeine can have an unhealthy affect on insulin levels

"We found that obese individuals have a resistance to insulin, which means they require higher levels of insulin to adjust their glucose levels. When given caffeine, their insulin levels go through the roof," says Graham.

Those with type-2 diabetes can still produce insulin – the body's blood glucose regulator – but according to Graham they can't produce enough to "get the job done," and often have to take drugs to manage their blood sugar levels.

Caffeine could push some over the edge

The researchers don't know if coffee affects insulin resistance in the same way pure caffeine does. Graham says that in other circumstances, they've found that coffee and caffeine affect the body differently.

The new research at the University of Guelph, University of Waterloo and Queen's University will involve four groups of 12 to 18 people between the ages of 40 and 60. There will be an equal mix of obese and lean people with and without type-2 diabetes.

Depending on the health of the individual, Graham says, the added insulin resistance generated by coffee consumption could push those already at risk of acquiring diabetes over the edge.

But the good news is that regular exercise can reduce the insulin resistance associated with caffeine consumption.

Rather than cutting out caffeine altogether, the researchers suggest the key is a mix of moderate caffeine consumption and a balanced, healthy lifestyle.

The team's earlier research was published in The Journal of Applied Physiology.