Cataract with diabetes. The risks?!

My mom was diagnosed with cataract in April 2015, still not operated. As per her yesterday Blood sugar report Fasting is 188 and PP is 219. She has extreme blurred visibility in her right eye. Doctors of private hospitals says they can do the surgery however Govt hospitals asks her to get the level of Glucose PP down to 100 which is not happening before they can do the surgery. My query is whom to believe, what kind of risks are involved and are the pvt. doctors just wanting to make money and not considering the risks???!!!! FYI my mom is only about 45-49 kgs and controls extensively, does brisk walking, eats karela,neem and what not to bring down the level but just not happening and in turn getting weaker day by day...