No, a request for your medical is not a sign of approval. If the CIC asks you for your medical, it only means you are one step closer, but there is no guarantee of approval. First off, you will have to actually pass the medical to proceed further. CIC will check for certain conditions, such as syphilis, tuberculosis, diabetes, HIV and AIDS, etc.. to determine if you can even be admitted into Canada. You should not have to worry if you small, minor conditions, ailments or diseases, as CIC only wants to see if you will place great strain on their medical system (defined as a disease costing more than CAD$20,000 over the period of five years to treat) or if you will pose a danger to public health. Small diseases generally do not warrant medical inadmissibility.