Granulomas galore: Twin cases of insulin-induced granulomas

Suppurative granulomas at insulin injection sites are exceedingly rare. While localized reactions such as erythema, pruritus, and lipodystrophy are well documented, granulomatous inflammation features merit increased clinical awareness. We describe two young adults – a 27 year old male and a 20 year old female with type 1 diabetes – who developed firm, tender, nodular, and ulcerated lesions with occasional pus discharge at thigh, abdomen, and shoulder injection sites 1 month after switching from premixed to separate regular and neutral protamine hagedorn (NPH) insulin. Both reported improper mixing technique, syringe reuse, and suboptimal storage. Investigations ruled out infection, immunodeficiency, and retained foreign bodies. Histopathology revealed suppurative foreignbody type granulomas with central vacuolation in giant cells, without insulin crystals. Cultures and special stains for bacteria, fungi, and mycobacteria were negative. These presentations are highly unusual and likely represent insulin- or zinc-induced noninfective granulomatous inflammation exacerbated by improper handling and injection hygiene. Proper mixing technique, hygiene education, and use of premixed insulin resulted in rapid lesion resolution. Clinicians should recognize this rare complication, ensure patient education, and investigate potential contributing factors to minimize recurrence.