Diabetes is a disease characterized by an excessive level of glucose in the bloodstream, which may be a result of improper insulin secretion. Insulin is secreted in a bursting behavior of pancreatic $\beta$-cells in islets, which is affected by oscillations of cytosolic calcium concentration. We used the Dual Oscillator Model to explore the role of calcium in calcium oscillation independent and calcium oscillation dependent modes and the synchronization of metabolic oscillations in electrically coupled $\beta$-cells. We implemented a synchronization index in order to better measure the synchronization of the $\beta$-cells within an islet and we studied heterogeneous modes of coupled $\beta$-cells. We saw that increasing calcium coupling or voltage coupling in heterogeneous cases increases synchronization; however, in certain cases increasing both voltage and calcium coupling causes desynchronization. To better represent an islet, we altered previous code to allow for a greater number of cells to be simulated.