Maturity onset diabetes of the young (MODY) accounts for 1% of diabetes in the UK but the young age of diagnosis, high glucose values in slim patients and lack of professionals' familiarity with the family history often lead to a misdiagnosis of type 1 diabetes. The identification of six different genes that cause MODY means that genetic testing may confirm the diagnosis and define the subtype. MODY patients with a mutation in the hepatocyte nuclear factor-1 alpha (HNF-1 alpha) gene are known to be particularly sensitive to the hypoglycaemic effect of sulphonylureas which has implications for their treatment. In depth interviews were conducted with 18 HNF-1 alpha MODY patients, on insulin from diagnosis, who were offered the possibility of transferring to a sulphonylurea. A qualitative approach was used to gain an in depth understanding of their perceptions about stopping insulin. Six key themes emerged: (i) concern and anticipation about the prospect of stopping insulin; (ii) interactions with health care professionals; (iii) the impact on glycaemic control; (iv) improved lifestyle and self-image; (v) reflections regarding the time on insulin; and (vi) difficulty in ‘letting go’ of insulin treatment. Transferring insulin treated HNF-1 alpha MODY patients to sulphonylureas was safe in the short term. All 18 patients reported positive lifestyle changes and most showed no deterioration in glycaemic control, although the progressive nature of HNF-1 alpha MODY means they are likely to need insulin again in the future. These findings have implications for other patients able to stop insulin after many years, such as those undergoing islet cell transplantation. Copyright © 2003 John Wiley & Sons, Ltd.