Depressed patients are up to 60 per cent more likely to develop diabetes, a study found.
Researchers discovered a genetic link between the two illnesses to explain why they often occur at the same time.
The scientists from King’s College London hope their findings will pave the way for new treatments that can cure both diseases simultaneously.
They are undertaking the largest ever study of its kind involving 160,000 pairs of twins to explain the link.
Experts have long known that patients with diabetes are more likely to be depressed, and vice versa, and until now they presumed it was coincidental or due to lifestyle.
But the study’s early findings show that genetic flaws are the main reason for both illnesses occurring at the same time.
In 87 per cent of men who had diabetes and depression, genes were to blame.
The link was slightly less strong in women, with both illnesses and genes responsible for up to 75 per cent of cases, they found.
Overall, they have established that patients with depression are 60 per cent more at risk of diabetes, and those with diabetes 15 per cent more likely to develop depression.
Dr Carol Kan, of the Department of Psychological Medicine at the Institute of Psychiatry, Psychology and Neuroscience at King’s, said: ‘These findings go some way towards explaining why diabetes and depression sometimes occur together, although further research is needed to explore the effect of gender in this interplay between genetic factors and environmental influences, such as diet and lifestyle.
'A better understanding of the mechanisms underlying these disorders and why they sometimes exist in tandem could one day provide useful biological targets for therapeutic interventions.’
The findings will be presented later today at the Royal College of Psychiatrists’ International Conference in London.
Almost 5million Britons are thought to be living with depression and 4million have diabetes, but numbers with both are unknown.
Researchers are not clear why the link exists but suspect the same genetic flaw may trigger both.
They hope further analysis will provide a more detailed explanation.