A blood glucose test instrument kit having modular component parts capable of being assembled into a plurality of different handheld blood glucose test instruments is disclosed. The kit comprises the combination of an interconnection platform adapted to connect to a collection of interoperable modules. The collection of interoperable modules including: a plurality of different measurement engine modules, at least one user interface module, at least one power supply module. A handheld blood glucose test instrument is assembled by the interconnection to the interconnection platform of at least one measurement engine module, at least one user interface module, and at least one power supply module. The inter-module communication among the modules connected thereto to achieve enhanced glucose test instrument reliability by effecting at least one reliability protocol selected from a group of reliability protocols.