Update: I was able to control my blood Sugar levels again with diet once Mirena removed and affect of glucose tolerance is now listed in US FDA Warnings and Precautions list for Mirena.
Not all that helpful for people who don't already know the symptoms of hypoglycaemia however and I have heard that others who developed Reactive Hypoglycaemia from Mirena have then become stuck with the condition.
The best results I have had drug wise dealing with reactive hypoglycaemia is by taking Metformin which is usually prescribed for diabetes. It just helps keep levels balanced and allowed me to eat bread occasionally.
The best results I have had diet wise is by adopting a mostly raw vegan diet. On this diet, while still taking Metformin, I was able to eat fruit again and even have the odd agave sweetened raw vegan desert.