The Ace of Spades hitmaker has been out of action since undergoing heart surgery, with reports in June (13) suggesting he had a implantable cardioverter defibrillator fitted.
Campbell has now confirmed the news, but has assured fans the 67-year-old frontman is well on the road to recovery.
He tells WalesOnline.com, "Lem had a pacemaker fitted earlier in the year because he'd been suffering from irregular heartbeats, and then his diabetes started playing him up.
"But his ticker's (heart's) fine now and he's made sufficient changes to his lifestyle and diet in order to combat the diabetes, it's just that he felt he wasn't 100 per cent ready to go back on the road just yet.
"As a result we put the dates back a little bit to enable him to build himself back up to full fitness."
Lemmy's ill health has prompted the band to postpone their European tour until 2014 to allow the singer enough time to be stage ready.