Researchers at Group Health Research Institute in the US followed 4,434 obese adults from 1995 to 2008, all of whom had type 2 diabetes and were candidates for gastric bypass surgery.
They found that in two-thirds of cases, the patient's diabetes initially went away after surgery.
However, more than a third of these patients developed diabetes once again within five years of having gastric surgery.
In cases where a patient's diabetes went away following surgery, it typically did not return for a median of eight years.
Overall, more than half (56 per cent) of patients had no long-lasting remission of their diabetes following their gastric bypass.
Principal investigator Dr David Arterburn, a general internist and associate investigator at Group Health Research Institute, revealed: 'Our results suggest that, after gastric surgery, diabetes stays away for longer in those people whose diabetes was less severe and at an earlier stage at the time of surgery.'
The findings, which are published in the journal Obesity Surgery, underline the importance of preventing diabetes in the first place, he added.