Type x diabetes

Resulting from the loss of pancreatic Beta cells, type 1 diabetes has traditionally been considered a diagnosis affecting children and adolescents. However, it is increasingly apparent that it can occur at any age. Indeed, the 2015 NICE guidelines advice is not to discount a diagnosis of type 1 diabetes if an adult presents with a BMI of 25 and above or is aged 50 years or above. Topically, the new prime minister is a good example of such an atypical presentation. There is usually a desire both from the patient and health care professional to determine the type of diabetes at presentation with the increasing use of auto antibodies to aid the diagnosis. Islet Cell Antibodies (ICA, against cytoplasmic proteins in the beta cell), antibodies to Glutamic Acid Decarboxylase (GAD-65), Insulin Auto antibodies (IAA), and IA-2A, to protein tyrosine phosphatase are often measured at diagnosis (GAD and PICA being the most common). Auto antibodies against GAD 65 are found in 80% of newly diagnosed patients with type 1 diabetes at clinical presentation whilst the presence of ICA and IA-2A at diagnosis for type 1 diabetes range from 69-90% and 54-75%, respectively. IAA prevalence correlates inversely with age at onset of diabetes and is usually the first marker in young children at risk for diabetes being found in approximately 70% at time of diagnosis. However, NICE advises routinely against testing for these antibodies apart unless the presentation has unusual features such as age and BMI>25 with the caveat that antibody tests have their lowest false negative rate at the time of diagnosis, and that the false negative rate rises thereafter. Overall, whilst antibody testing has its place, clinical impression and the priority to keep the patient safe from ketosis (which may require early use of insulin) should take priority over an early decision about diabetes sub type which usually becomes obvious with time.

Dr Mark Freeman