Sharing the news with her 123k followers on her Twitter account, the Channel 4 reality star explained that her sibling had been battling with dementia.
'MY SISTER PASSED AWAY THIS MORNING. SHE HAD DEMENTIA. AM ON MY WAY TO SEE HER AND FAMILY'S. WANT BE ON LINE FOR FEW DAYS. BUT AM OK EVERY 1,' she wrote.
The next day, Sandra also posted a second tweet which read: 'Morning all. AM ok..my sister is safely tucked away in God's grace. Last night I couldn't believe how much u can get mad during being sad.'
QUEEN BEE pic.twitter.com/P06c9T9eyZ— LADY QUEEN BEE OBE (@sandragogglebox) August 17, 2017
Fans have rushed to send their condolences to Sandra and her family.
'Sorry to hear this sad news .Sending lots of love and hugs to you and your family,' one wrote, whilst another said: 'So sorry for your loss. In my thoughts and prayers'.
'It's a very cruel disease 😢 I lost my mum to early onset alzheimer,' a third empathised, followed by one who agreed: 'Thoughts are with you ! My mother went the same way along with a stroke last year.i know it's not a real comfort but she is in a better plc.'
Fellow cast members Leon and June also reached out to Sandra to offer a message of support, commenting: 'So very sorry to hear of your sad loss Sandra. Our thoughts are with you and your family tonight!'
Sandra, 54, told fans that she would still be watching the other half of her Gogglebox sofa duo, Sandi Bogle, on the most recent series of Celebrity Big Brother despite the difficult circumstances.
'MY SISTER WAS A FAN OF ME ON ALL TV SHOW,' she said.. 'SO EVEN THOUGH SHE GONE.SHE WOULD OF SAID THE SAME TO CBB. SO AM JUST KEEP IT REAL. UGETME XXXX'