Improvement and Retention of Insulin Secretion in Slowly Progressive Type 1 Diabetes Mellitus by Diet Therapy and Exercise for Five Years

There are no clear strategies for non-insulin-dependent slowly progressive type 1 diabetes mellitus (SPIDDM). We herein report a 25-year-old man with SPIDDM in whom appropriate diet therapy and exercise improved the initial insulin secretion without medication. After 12 months, his body weight decreased by 5.4 kg, and his muscle mass increased from 0.77 to 0.81 kg/body weight. Glycated hemoglobin levels were reduced from 6.4% to 5.7%. HOMA-IR decreased from 1.70 to 0.77; in particular, the insulinogenic index improved from 0.04 to 0.13. These improvements were maintained over five years with continuous lifestyle interventions. Patients with non-insulin-dependent SPIDDM may recover and retain their insulin secretion through lifestyle interventions.