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

Paul Zimmet, Robert Turner, Daniel McCarty, Merrill Rowley, Ian Mackay

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127 Citations (Scopus)


Two major types of diabetes have been recognized since the late 1930s. However, in recent times there have been major changes in classification and understanding of these types, including improved knowledge of maturity-onset diabetes in the young, with the identification of mutations relating to impaired insulin secretion and the recognition of slow-onset type 1 diabetes in adults now designated as latent autoimmune diabetes in adults (LADA). A major problem area in diabetes classification concerns cases of slowly progressive forms of type 1 and type 2 diabetes, particularly in adults aged 25-50 years. This is a more contemporary problem because cases of type 2 diabetes are presenting at an increasingly younger age. In the landmark U.K. Prospective Diabetes Study of type 2 diabetes, islet cell antibodies (ICAs) and antibodies to glutamic acid decarboxylase (anti-GAD) were measured at diagnosis in 3,672 patients. The overall proportion with ICAs was 6%, and anti-GADs was 10%. These subjects dearly had type 1 diabetes or LADA by both phenotypic and genotypic features. The presence of auto antibodies correlated particularly with a younger age and phenotypic features consistent with type 1 diabetes (e.g., early age at diagnosis, lower BMI, and reduced β-cell 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 years. Antibodies to GAD indicate an underlying autoimmune process and have a high positive predictive value for type 1 diabetes and future insulin dependency in adults.

Original languageEnglish
Pages (from-to)B59-B64
JournalDiabetes Care
Issue numberSUPPL. 2
Publication statusPublished or Issued - 1999

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism
  • Advanced and Specialised Nursing

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