Why does having health insurance before being diagnosed with a serious condition make a difference?

Will a health insurance that I just got, cover for a diabetes condition that hasn't been diagnosed yet?

• We don't have health insurance, but now that I finally got a good job that offers health insurance I was planning on get coverage for me and my husband. Both of us are very healthy and we only get sick once in a while with a mild cold or flu. Our coverage starts on January but last Sunday we went to a Free Health Fair and we found out that my husband is diabetic, his sugar level was extremely high, to the point that it was scary. The weird thing is that he was feeling perfectly fine. My concern now is, if my health insurance will cover for his diabetes. He has no previous medical records that could show this condition, but if we wait until January and then they diagnose him with diabetes, can they deny coverage?

• Answer:

  Disease which has been diagnosed prior to taking insurance policy are not covered. Insurance companies normally get the medical done before issuing policies.