How to make an indicator function or handle for glmfit?

Hi everyone, I have a question about creating a handle or indicator function. I have a X matrix that contains 4 explanatory variables and one column (the last one, column 5) of ones and twos that indicates if the observation belongs to group 1 by 1 or group 2 by 2. I want to perform 2 glmfit. One for the observations belonging to group 1, and one for the observations belonging to group 2. I thus need some kind of indicator function so that the glmfit will only calculate the observations of the specific group. Can somebody help me how I can so this? I make use of the following glmfit: [B1, dev, stats1] = glmfit(X(:,1:4), Y, 'binomial', 'link', 'logit');