There are two situations.
I buy a policy, while I don’t have diabetes. Once policy is issued and I develop some symptoms of diabetes later one. Naturally,I will try to stay fit. But if any hospitalization happens and I need claim, All insurance companies will cover it. Every company covers diabetes and relayed complications after issuance of policy.
Other situation, I am already diabetic. Now there are two type of policies. Normal policies and policy for diabetic people. Normal policies of all Companiws will take Diabetes as pre existing disease and will cover after a certain waiting period. Minimum is TWO and maximum wait period in India is four years.
Now, there are three types of policies for diabetic patient. All of them are bit different, but covers complications due to diabetes after first day, 30 days and 90 days respectively.
I will reveal a secret. All insurance companies have a standard policy. 98% of insurance products in health insurance are theae standard products. All companies have similar policies. If you get a claim in one, all other Companies will also settle the claim. If a claim is rejected one one, all others will also reject the claim. Because, inherently, all health insurance policies are 100% same. There is no such thing as best or superior health Insurance company or policy.
A mobile from Apple, Samsung or xiaomi are basically a phone. It is suppose to call and receive calls. In that analogy, Health insurance policy of Star, Apollo, United, Icici, Religare, Max Bupa……all have same policy.
Coming to original question.
Yes, Diabetes is covered in Star health Insurance.