Researchers from the University of Pittsburgh in the US found that the risk of increased mortality associated with intensive therapy was outweighed by the benefits.
Intensive treatment, a method of treating type 1 diabetes now widely accepted in the UK, involves patients monitoring their blood glucose levels and receiving multiple daily insulin doses.
It commonly takes the form of multiple daily insulin injection (MDI) or continuous subcutaneous insulin infusion (CSII) therapy.
The aim of the treatment is to achieve glycaemia as close to the non-diabetic range as is safely possible.
But the therapy has been associated with an increased risk of developing hypoglycaemia, which in turn has been linked to an increased risk of mortality.
The initial Diabetes Control and Complications Trial (DCCT), carried out in the US between 1983 and 1993, found that intensive therapy reduced morbidity in patients with type 1 diabetes. However, the long-lasting effects of intensive therapy on mortality were less clear.
In the initial study, 711 patients received intensive therapy and 730 conventional therapy, which involves just one or two insulin injections daily. The latest study looked at more than 1,400 patients from the original study and followed their progress through annual contact for an average 27 years.
It found that the risk of all-cause mortality was lower in the intensive group than the conventional group, although the absolute risk reduction was small. During the study, 6% of patients who had been in the intensive group died, compared with 9% in the conventional group.
'The current data suggest net mortality benefit from intensive therapy,' the researchers said.
Surrey GP Dr Neil Munro, former chairman of Primary Care Diabetes Europe, said the results 'supported the continuing practice' of MDI and CSII therapy in patients with type 1 diabetes.
He said: 'This study is of particular interest in view of its duration. The authors acknowledge that the event rate was very low, which makes firm interpretation problematic.
'However, in the people with type 1 diabetes under the age of 40 followed up for 27 years, it is reassuring to see that intensive insulin treatment - and its attendant risk of hypoglycaemia - does not result in adverse overall outcomes compared with less intensive insulin therapy.'