We report the case of a 39-year-old female patient with acute painful swelling of the left thigh and symmetric muscle weakness in both upper legs. The patient had a history of long-standing, poorly controlled type 1 diabetes and required dialysis due to diabetic nephropathy. At admission serum inflammatory markers were highly elevated. MRI showed liquid formation in the adductor magnus muscles, indicating necrotic or inflammatory colliquation. As antibiotic therapy did not lead to clinical improvement anti-inflammatory therapy with prednisolone was initiated which led to rapid improvement. Three months later, the patient presented with a new onset of progressive and painful muscle swelling of the right thigh. MRI showed pronounced swelling of the right adductor muscles and inflammatory markers were massively elevated. In the absence of autoantibodies or any infectious agents and the recurrent symptomatology relapsing diabetogenic, myonecrosis was diagnosed. Initially, clinical improvement could only be achieved with high dose glucocorticosteroids. Intravenous immunoglobulins did not show an effect, whereas serological and clinical remission was achieved after we administered tocilizumab intravenously. Diabetic myonecrosis is a rare complication of long-term, poorly controlled diabetes mellitus. Acute muscle pain and elevated inflammatory markers in diabetes patients should prompt suspicion. Contralateral muscle involvement in the patient history is also suggestive of the disease. The optimisation of diabetes treatment is crucial in order to prevent further disease complications.