The 32-year-old was diagnosed with Type One Diabetes when he was in Year 9, and struggled to manage the condition, and was dependent on daily insulin injections.

He was repeatedly hospitalised and was often in intensive care in his twenties due to diabetic ketoacidosis.

The chronic disease impacted his mood and his ability to work and his ability to maintain relationships.

Jano and Paul Yousseph are organising the fundraiser to honour Sebastian, and are friends of his parents Richard and Belinda.

"Sebastian's passing affected us immensely," he said.

"Type One diabetes affects so many families, with Jano being diagnosed recently in her early fifties, her nephew being diagnosed as a young teen and many other close friends whose children were diagnosed at a much younger age."

Through the fundraiser, Paul wanted to highlight the daily struggles, and how it affects people.

"It's important because there's not enough conversations around Type One Diabetes and the mental health aspects," he said.

The goal is to raise $100,000 and increase awareness for Type One Diabetes and at the time of publication, close to $33,000 has been raised.

The cyclists will make their way from Bella Vista to Bowral on April 21 to support Diabetes Australia, and JDRF Australia - a not-for-profit dedicated to advocacy, research and supporting people living with Type One Diabetes.

The journey will finish at Glebe Park between 12.30pm and 1pm, and will include 1.6 kilometres of climbing.

There will be a barbecue at the finish line and everybody is welcome to attend.

"People living with diabetes have to make numerous decisions to manage this chronic condition every day, with what can feel like no end in sight," Paul said.

"Our hope is to find better ways to support the mental and physical health for people with Type One Diabetes.

He said he hoped it would become an annual fundraiser.

Head to bluearmy.jdrf.org.au/fundraisers/sebastiansjourney/sebastian--s-journey to learn more and donate.