An Investigation into the Causes of Insulin Aggregation

Insulin is an essential peptide hormone that aides in the metabolism of glucose by allowing the cells to uptake glucose. Exogenous insulin is often prescribed to patients in order to help manage their diabetes. Recent research has indicated that prescription insulin is not at the labeled concentration when the prescription is filled by the patient. This decrease in concentration from when the insulin is manufactured to when it reaches the pharmacy is likely due to the insulin denaturing and aggregating. Dynamic light scattering is a useful and accurate method to determine the hydrodynamic radius of a solute and can be used to measure the hydrodynamic radius of insulin which will thus determine the aggregation of the sample since the more aggregated it is, the larger the hydrodynamic radius will be. By testing the effect of pH, concentration, temperature, and time on insulin samples, the optimal storage conditions can be determined in order to ensure researchers and patients are not using aggregated insulin. No conclusive relationship was found between any variable and sample diameter, but several trends were identified. Temperature, pH, and time in solution are all factors that could impact the aggregation, and therefore activity, of insulin. However, concentration did not show any trend regarding aggregation. Determining the relationships between these variables could allow for the identification of ideal storage conditions for researchers. Additionally, it can be used to identify shortcomings in the insulin supply chain.