We report a 49-year-old woman with severe diabetic scleredema (DS). The patient had non-insulin-dependent diabetes mellitus (NIDDM) for 9 years and noticed thickened skin on her back 3 years previously. Her DS rapidly extended to her back and extremities with pain and immobility. Her symptoms of DS improved dramatically after establishing strict glycemic control and intravenous administration of prostaglandin E1 (PGE1). However, the histological findings of her skin biopsy did not change even after the treatment for 12 weeks, and her symptoms worsened again after discontinuation of glycemic control and PGE1 treatment. The causes of DS have been considered to be metabolic abnormalities associated with hyperglycemia and hypoxia in the skin due to diabetic microangiopathy. PGE1 was an effective treatment for DS in our patient. Strict control of hyperglycemia and PGE1 treatment may be sufficient to manage DS, although a very long treatment period is necessary.