A 24‐year‐old Indigenous Australian female with long‐standing, poorly controlled type 1 diabetes mellitus (T1DM) presented with 3 months’ history of unilateral thigh swelling and pain. Her laboratory investigations showed evidence of a persistent inflammatory state with normal creatine kinase. Infectious and autoimmune investigations were negative. Imaging demonstrated evidence of muscular oedema and atrophy. Muscular pain and swelling have a broad list of differential diagnoses. This case highlights a rare but potentially debilitating complication of diabetes mellitus—diabetic myonecrosis with its challenges in reaching a definitive diagnosis due to non‐specific symptomology and laboratory findings. However, it is an important differential of leg pain and swelling to consider, particularly in those with long‐standing diabetes and pre‐existing microvascular complications. Glycaemic control is paramount in preventing this potentially severe diabetic complication.