Acromegaly is generally caused by a benign growth hormone (GH)-secreting pituitary adenoma. It is characterized by a wide range of complications; cardiovascular, respiratory, bone and joint, and metabolic complications. Among them, impaired glucose tolerance and diabetes mellitus, due to GH-induced insulin resistance, has been reported in approximately 16-46% and 19-56%. They are usually improved following the treatment of acromegaly, surgical or medical therapy. We report a first case of 36-year-old man who was paradoxically diagnosed with GAD antibody positive latent autoimmune diabetes in adults (LADA) after the surgical cure of acromegaly.