Reversal of Type 2 diabetes after bariatric surgery is determined by the degree of achieved weight loss in both short- and long-duration diabetes.

AIM: To define the impact of duration of diabetes and extent of weight loss on the reversibility of Type 2 diabetes after bariatric surgery.
METHODS: Complete data were collated from 89 individuals with Type 2 diabetes mellitus undergoing any bariatric surgical procedure in a specialist bariatric centre. People with a preoperative HbA1c < 43 mmol/mol (6.1%) were excluded. Diabetes duration was defined as: short, < 4 years; medium, 4-8 years; and long, > 8 years.
RESULTS: An HbA1c of <43 mmol/mol (6.1%) was achieved by 62% of patients in the short-duration group and 26% of patients in the long-duration group. Normoglycaemia was rarely achieved in the long-duration group if weight loss was < 25 kg. In the whole cohort there was a clear relationship of greater weight loss with lower HbA1c levels (Rs = -0.53; P < 0.0001).
CONCLUSIONS: The study shows that the degree of achieved weight loss is the major determinant of return to normal blood glucose levels after bariatric surgery. Normoglycaemia can be achieved in long-duration Type 2 diabetes, but a greater degree of weight loss is required than for short-duration diabetes.