Endocrine Abstracts

Introduction: Clinicians are hopeful for substantial weight loss after surgical intervention for obesity, with the funding decisions relatively easier to achieve in those with diabetes, there is a significant proportion of these patients undergoing procedures. In contrast to most outpatient encounters, a 20 kg drop in weight is looked upon favourably between follow-ups where it would have risen the spectre of pathology elsewhere. We present the following case that illustrates an unexpected pitfall.

Case: 51 year old male with a weight of 162 kg (BMI 49) is diagnosed with type 2 diabetes mellitus (T2DM). He has no medical history besides a son with Addison’s. He is started on metformin therapy and referred to the local obesity team for weight management. His diabetic control is proving difficult and he has had a rapid treatment intensification with sulphonylureas, SGLT2 inhibitors and GLP-1 agonists. After 18 months, he undergoes a Roux-en-y Gastric Bypass. The operation proceeds successfully. On first review, his weight has dropped to 140 kg (BMI 42) and the team is pleased with the improvement in his weight. 12 months later and he has left his previous area. At his first appointment in our Diabetes centre he weighs 92 kg (BMI 28) with a HbA1c of 86. His weight loss of 70 kg in 18 months has suspiciously had no benefit on his diabetes control. He is started on basal Lantus. His HbA1c continues to rise thus he was switched to the longer-acting toujeo. There is a supply issue and his lantus runs out two days before his toujeo can start. He is admitted in euglycaemic ketoacidosis. Diabetes associated antibodies are tested. All are strongly positive. He is treated for type 1 diabetes mellitus (T1DM).

Discussion: We present this case to highlight that weight loss post-gastric intervention in the diabetic population can be a pathological presentation of type 1 diabetes. A “honeymoon” T1DM can easily be mistaken for a T2DM. The authors would recommend formal testing for type 1 diabetes if a post-operative patient with a family history of autoimmune disease a) experienced rapid and sustained weight loss and b) required frequent diabetic treatment intensification.