Making a diagnosis of Type I DM is of paramount importance as early as possible to start on correct treatment. Some patients may not present with classical symptoms of ketoacidosis. In fact some may be adult with overweight with maintained residual b-cell function, leading to a misclassification as type 2 diabetes. Four autoantibody specificities have been shown to be relevant for the diagnosis:Autoantibodies against glutamic acid decarboxylase (anti-GAD) positive in 70�80% of children and adults with type 1 diabetes, Autoantibodies against tyrosine phophatase (anti-IA-2) present in 50�70% of children and in 30�50% of adults. Insulin autoantibodies (IAAs) are detectable in 50�70% of children and in 20�30% in adults. Cytoplasmic islet cell antibodies (ICAs) are positive in 80�90% of newly-diagnosed patients with DM type I
Combined screening for IAA and anti-GAD (age less than 10 years) or IA2-Ab and anti-GAD (age over 10 years) is the recommended first-line analysis. The detection of one autoantibody provides evidence of an ongoing autoimmune process. A special form of type 1 diabetes is the so-called latent autoimmune diabetes in adults (LADA). These patients typically develop diabetes after the age of 30 years and have a slowly progressing autoimmune process. Therefore, endogenous insulin secretory capacity is only slightly decreased at the manifestation of the disease. Due to clinical features, these patients are often misclassified as suffering from type 2 diabetes and are treated with oral hypoglycemic drugs. After several months or a few years, these patients develop absolute insulin deficiency and require insulin treatment. In young and middle-aged adults, the frequency of this form of diabetes is relatively high (approx. 20% of patients with type 2 diabetes in the age range 25�44 years). The detection of LADA should be made by primary screening for anti-GAD, ICA or Anti IA-2
It is recommended that any patient with suspected type I or type II diabetes, especially when clinical presentation is not typical to ask for the above antibodies
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