Crucial points at diagnosis - Type 2 diabetes or slow type 1 diabetes

Two major types of diabetes have been recognized since the late 1930s. Howe ver, in recent times there have been major changes in classification and un derstanding of these types, including improved knowledge of maturity-onset diabetes in the young, with the identification of mutations relating to imp aired insulin secretion and the recognition of slow-onset type 1 diabetes i n adults now designated as latent autoimmune diabetes in adults (LADA), A m ajor problem area in diabetes classification concerns cases of slowly progr essive forms of type 1 and ripe 2 diabetes, particularly in adults aged 25- 50 years. This is a more contemporary problem because cases of type 2 diabe tes are presenting at an increasingly younger age. In the landmark U.K. Pro spective Diabetes Study of type 2 diabetes, islet cell antibodies (ICAs) an d antibodies to glutamic acid decarboxylase (anti-GAD) were measured at dia gnosis in 3,672 patients, The overall proportion with ICAs was 6%, and anti -GADs was 10%, These subjects clearly had type 1 diabetes or LADA by both p henotypic and genotypic features. The presence of auto antibodies correlate d particularly with a younger age and phenotypic features consistent with t ype 1 diabetes (e.g., early age at diagnosis, lower BMI, and reduced beta-c ell function). Overall, of patients requiring insulin by 6 years, 38% were anti-GAD(+) at baseline compared with 5.3% of those not on insulin at 6 yea rs. Antibodies to CAD indicate an underlying autoimmune process and have a high positive predictive value for type 1 diabetes and future insulin depen dency in adults.