Abstract
Hyperglycaemia is one of the most common metabolic disturbances encountered in clinical practice, with an important differential diagnosis. We report a case of a 72-year-old woman referred to diabetes services with rapidly increasing blood glucose and weight loss despite oral hypoglycaemic therapy. She reported mild upper abdominal discomfort and liver function tests were deranged, prompting further investigation. Abdominal imaging demonstrated a diffusely enlarged pancreas and subsequent investigations noted a markedly raised serum IgG4. She was diagnosed with IgG4-related pancreatitis and swiftly responded to steroid therapy. Secondary causes of diabetes should be considered in people with atypical presentation such as weight loss or rapid progression to insulin use. While IgG4-related disease is rare, its varied clinical presentation as a result of its multiorgan involvement requires a high index of suspicion. This case highlights the importance of a detailed diagnostic work-up and describes an unusual clinical presentation of this increasingly recognised multisystem disease.