1. A neural network device, comprising: an input layer configured to accept N input signals; one or more “i” hidden layers having memory; at least one output layer; at least one neuron “Y layer ” within each layer, where “layer” is the layer defined as “input”, “hidden i ” or “output”; and one or more memory structures configured to: a) store a recursive memory of input signals past, and b) allow for at least one time series prediction of a response; wherein one or more memory structures are included in both the input and hidden layers; and wherein the device is configured to be a time-lagged feed forward neural network device for predicting analyte levels in a sample or a subject in need thereof.