To clarify whether elemental changes are present before the onset of diabetes, freeze-dried pancreas sections from young (18-19 days-old), genetically prediabetic Chinese hamsters were subjected to proton bombardment and the concentrations of 15 elements (Na, Mg, Al, P, S, Cl, K, Ca, Mn, Fe, Cu, Zn, Rb, Cd, and Pb) in B cells and exocrine pancreas were calculated from the x-rays emitted. We have previously shown that islet B cells and exocrine pancreas from adult, overtly diabetic Chinese hamsters contain subnormal levels of Al (-61%, -88%) and excess levels of Cu (+92%, +59%), Rb (+13%, +13%), and Mg (+6%, +6%) in B cells and exocrine pancreas, respectively (Juntti-Berggren et al., Biosci Rep 1976; 7:3341). In the present study the prediabetic B cells contained normal levels of all 15 elements, whereas the prediabetic exocrine pancreas contained a subnormal level of Fe (-10%; p < 0.005). Hence, the development of diabetes in the Chinese hamster does not seem to be associated with an early change in the elemental composition of the pancreatic B cells. In fact, the overt diabetic condition may cause changes in the body's handling of some elements.