Type 1 diabetes results from a chronic autoimmune destruction of the pancreatic beta cells and accounts for about 10% of all patients with diabetes. The pathogenesis includes genetic and environmental factors. The disease is preceded by a pre-diabetic period with progressive beta cell destruction and formation of islet related autoantibodies. Histological analysis of post mortem specimens from pancreas donors did not reveal insulitis in individuals with islet autoantibodies. In contrast, in newly diagnosed T1D patients beta cells may be present and various degree of insulitis with infiltration of macrophages and CD4 + and CD8 + T-cells is seen. At the final stage islets are devoid of beta cells and inflammatory infiltrates. IAPP, is a beta cell hormone, secreted together with insulin upon glucose stimulation. Over the years, IAPP has been ascribed a wide range of biological functions, most of which are involved in glucose homeostasis. Identification of IAPPreceptors on beta cells, point to an auto- or paracrine function for IAPP. Increased insulin secretion in IAPP deficient mice in Danshensu response to an oral glucose load supports an intra-islet function. Also infusion of an IAPP-specific receptor antagonist during a hyperglycemic clamp augmented insulin secretion in parallel with a proportional increase in glucose disposal rate. In a patient with a malignant pancreatic tumour circulating IAPP was determined to be 400 times higher than normal basal IAPP levels. Metabolic characterization of the patient showed that insulin secretion was fully blocked while the peripheral insulin sensitivity remained unaffected. IAPP-amyloid is present in the islets of Langerhans in almost all individuals with type 2 diabetes, but is also seen in other conditions associated to beta cell stress, such as islet transplantation. The complete pathway for protein misfolding needs to be identified but high IAPP concentrations are believed to be one factor important for initiation of aggregation. Amyloid Cryptochlorogenic-acid fibrils are formed via smaller intermediates often referred to as oligomers or protofibrils, and the general perception is that certain oligomeric species are cytotoxic, and therefore is the formation of amyloid fibrils is considered to be more harmful than the deposited amyloid itself. However, growing amyloid deposits will interfere with cell-cell signalling and nutritional transport. It is unknown whether IAPP-aggregation has any function in the development of T1D. One can assume that during beta cell destruction that precedes T1D, remaining beta cells are exposed to an increased functional demand similar to that in type 2 diabetes. Therefore, the aim of this study was to determine if IAPP levels were linked to decreased C-peptide levels seen in T1D. With the use of ELISA, IAPP autoantibodies were detected in 18% of analysed plasma samples from patients with T1D. However, if autoantibodies against human IAPP would contribute to the high IAPP concentrations cross-reactivity must occur between the murine capture antibody and human immunoglobulins. It should be pointed out that the high frequency of IAPP autoantibodies in T1D has been contradicted. Also, when a radiobinding assay was used, that is considered to be more specific than ELISA, IAPP-autoantibodies could only be detected in 3 out of 65 T1D plasma samples.