"He put off the doctors for weeks after he first started experiencing the symptoms because he was afraid of what they would find," the source said.
"Now the prison docs are telling him they believe he has a brain tumor. They plan to run a series of tests on him, MRIs and CT scans."
The Enquirer reports that Simpson has finally agreed to the tests and is convinced he hasn't got long to live, telling a friend, "I feel the end coming. But I don't want to die in prison like common jailhouse scum."
The publication reports he has even begged President Obama for a pardon so he can die comfortably at home.
Before Simpson is eligible for parole, he has to serve another four year of his 33 year sentence at the Lovelock Correctional Center.
The Enquirer reports Simpson tried to lose weight by sticking to a strict diet and exercise plan after a diabetes-related health scare a few months ago, but it was a struggle.
'He began suffering dizzy spells, nausea, lapses in memory and headaches - and the frightening symptoms continue to get worse,' the source is quoted as saying.
The article claims Simpson, in a last ditch attempt for freedom, wrote to the President and said "Mr President, I know my life is coming to an end. Please, don't let me die in prison."
In July, The Enquirer reported Simpson had just months to live as a result of his extreme case of diabetes and unhealthy lifestyle behind bars.
The combination of '"ky high" blood pressure, a vastly expanding waistline and a lack of physical activity had doctors concerned about his health, the magazine reported at the time.
All in the family: OJ Simpson's 43-year-old daughter testified at his May hearing and he is reportedly storing his money in off-shore accounts so she and his son can have it when he dies
Simpson's lawyer Ozzie Fumo told MailOnline that he has not heard anything about his client's poor health.
"As far as I know his health is very good, he was doing just fine," Fumo said. "I spent a lot of time with him preparing for the retrial motion and he never once mentioned diabetes.
'We discussed health issues, we had meals together, and he seemed fine."
The first warning signs came during a court hearing in May when the former running-back looked much heavier than he ever had before.
In the July story, The Enquirer claimed Simpson weighed 300 pounds and prison doctors encouraged him to exercise and eat more healthily to combat the high blood pressure and diabetes.
He had developed a habit of passing the days by laying in bed in his prison cell and only getting up to get sugar-filled snacks, it reported.
"OJ's doctors have told him he could be dead in as little as three months because of his out-of-control blood sugar and blood pressure," an unidentified prison friend told The Enquirer in the summer.
'But OJ doesn't care. He knows he's never going to get out of prison, so he refuses to take care of himself.'
The 33-years he faces following a 2008 robbery are not helping motivate Simpson, as he is now making plans for his death.
He allegedly confessed to murdering his ex-wife Nicole Brown and her friend Ron Goldman in 1994 and told a prison friend that he will write a confession letter that will be sent- and then publicly shared- after he dies.
Fumo countered this claim, saying that in his months of interactions with Simpson he has "never once disparaged the Goldmans".
"In his mind, they're creditors along with his children Sydney and Justin," Fumo said.
The friends cited by The Enquirer said the double slaying came in a moment of rage that he regrets to this day because he still loves Nicole.
- Daily Mail
