Clinical Characteristics of Slowly Progressive Insulin-Dependent (Type 1) Diabetes Mellitus (SPIDDM): 1st Subcommittee Report on SPIDDM, Committee on Type 1 Diabetes, Japan Diabetes Society

Abstract

To describe the clinical characteristics and prevalence of slowly progressive insulin-dependent (type 1) diabetes mellitus (SPIDDM), we conducted a nation-wide survey. We registered 687 diabetic patients with a history of diabetes of 5 years or less from April 2004 to December 2009 in our hospitals. Among them, 49 patients had SPIDDM, 425 patients had type 2 diabetes, and 58 patients had acute-onset type 1 diabetes. The frequency of SPIDDM patients was 10% (49/474, 95% confidence interval: 8-13%) among those with type 2 diabetes or SPIDDM. When compared with type 2 diabetic patients, SPIDDM patients showed significantly higher frequencies of autoimmune thyroid disease and insulin treatment at registration and significantly higher levels of HbA1c, and had significantly lower body mass index values. SPIDDM patients showed a significantly higher frequency of glutamic acid decarboxylase autoantibodies (GADAb) than insulinoma-associated protein 2 autoantibodies (IA-2Ab) or insulin autoantibodies (IAA), and showed a significantly higher frequency of single positive findings of autoantibodies among GADAb, IA-2Ab and IAA than patients with acute-onset type 1 diabetes. These results indicate that a high prevalence of SPIDDM was found in Japanese patients thought to have type 2 diabetes, and SPIDDM patients had specific clinical characteristics which differed from those with type 2 diabetes or acute-onset type 1 diabetes.