Muscle aching and weakness post exercise.

I have type 2 diabetes but enjoy quite strenuous exercise, (orienteering, cycling, swimming). I am controlled on Insuman 25. I seem to have got the BMs , calorie intake and testing around the exercise about right. No hypos during exercise or afterwards. I feel really good for a few hours after exercise but then I have is profound muscle aching to the point of gnawing restless discomfort, almost with a feeling of weakness all over-very unpleasant. I am used over the years, to having typical sports related muscle soreness in specific muscle groups! This is something else though, very unpleasant ,and lasts a couple of days. Currently putting me off exercising. Does anyone have any suggestions?