Relationships between abdominal obesity and glucose tolerance disorders have been well documented. There are also many reports concerning body weight gain during insulin therapy. On the other hand, there are reports pertaining to the effectiveness of surgical treatment of obesity and related type 2 diabetes. The case is presented of a 39-year-old woman with morbid obesity (maximum weight – 141 kg, BMI – 48.8 kg/m²), who reported to the outpatient department for metabolic diseases in December 2009. The patient had suffered from diabetes for 8 years and was treated with insulin – a dose of 114 IU from the day of the first visit. The patient received education concerning the modification of lifestyle, diet and insulin therapy. A balanced diet of 1,200 kcal daily was recommended. The daily insulin dose was reduced to 56 units. The patient was considered as a potential candidate for bariatric surgery. During the preparation for this procedure she was hospitalized in the Diabetology Ward, where the doses of insulin were further reduced and then discontinued. In March 2010, gastric sleeve resection was performed. Within 18 months, the patient’s body weight was reduced by 66 kg and normalization of glycaemia was obtained, despite the total discontinuation of anti-diabetic drugs. In addition, the remission of psoriatic changes was observed. Conclusions: In patients with type 2 diabetes and severe obesity, in whom a satisfactory metabolic control cannot be achieved with standard hypoglycaemic therapy, further intensification of insulin treatment does not have to be the method of choice, although it may lead to the normalization of glycaemia. In some patients there is the possibility of total remission of glucose intolerance due to bariatric surgery, irrespective of the previous method of treatment.