For example if the insured traveller is a diabetic and are is under continuous medication for diabetes, the same will be treated as a pre-existing condition and excluded under the policy. This means that if there is any treatment undertaken by the insured while abroad, and the attending physician deems that this is related to his/her diabetic condition, then the insurance company has the right to repudiate the claim. It is important to however note that if there is any treatment availed by the insured which is not related to the diabetic condition, then the same is covered under the policy.
Similarly, for a heart patient, if they are under continuous medication for the condition, the same will be treated as pre existing. Also If they have had the bypass surgery within 48 months prior to commencement of your travel/trip, then the same will be treated as a pre-existing condition under the policy and any claim/treatment occurring as a result of the surgery, will not be covered under the policy. Similarly if 48 months have elapsed since the surgery, but you are still under continuous medication for the bypass, the same will be treated as a pre-existing condition and excluded under the policy. However if there is any treatment availed by the insured which is not related to the diabetic condition, then the same is covered under the policy.
Some insurance policies have a limited coverage for pre-existing conditions in life threatening conditions inbuilt in their plans (this could vary between $1000 to $2500), this could provide some coverage subject to other terms and conditions of the policy, if the life threatening condition is a result of the insured being a diabetic/having a heart condition/hypertensive etc. Please note that if the condition is not life threatening, then this coverage will also not kick in.
The good news for all travellers with a pre existing condition is that there are some insurance companies which provide this coverage subject to prescribed limits, terms and conditions. The traveller can log onto https://eindiainsurance.com/
and check out the Pre Existing Coverage section to opt for such plans. It is strongly recommended that if the traveller has a pre existing medical condition, they avail a suitable plan (even if the coverage for such conditions is limited) prior to departing on their trip.