Please note that premiums will be higher than for diabetics, as people with diabetes will be considered a higher risk by insurance companies.
If you suffer from diabetes, insurers will want to know exactly how you control your condition, and you will probably be asked to undergo a medical test before you will be offered cover. This will usually involve sending your medical reports to insurance company and they may even request blood sugar readings.
The final premium will depend upon several factors, such as their last HbA1C reading, height and weight (BMI), blood pressure and cholesterol levels, and any other related medical issues or complications. There will be a significant impact upon the ‘loading' if a person with diabetes is also a smoker.
Online/Offline won't effect as in both cases your case will be referred for medical underwriting. Main point is declare everything in proposal form and in detail with supporting evidence.