The Maori King was admitted to hospital because of a "diabetes-related" ailment and is likely to remain there for at least another week.
King Tuheitia is understood to be still recovering in Waikato Hospital for a health-scare that sources yesterday said was a heart attack.
The King's spokesman Tukoroirangi Morgan said he became unwell on Sunday night having earlier attended Hamilton's 150th civic celebrations that day.
He was admitted to hospital in "some discomfort".
"After a thorough examination it can be confirmed that he did not suffer a heart attack," said Mr Morgan, in a media statement.
"His symptoms were consistent with the diabetes-related ailments for which he has been undergoing treatment over the past twelve months."
King Tuheitia's health specialists will run a series of tests, that will require him to remain in Waikato Hospital for at least another week, possibly longer.
Mr Morgan said the King had been overwhelmed with an outpouring of aroha and support since news of his admission to hospital was leaked.
"The family and the Kiingitanga would like to thank the nation for their well wishes," he said.
"To the rangatira of the motu, to the kaumaatua of Waikato and beyond, to all those thinking of him, he wishes to allay any undue fears over this latest setback in his ongoing recovery."
"He is grateful for receiving the very best treatments available and intends to return to official duties as soon as he is able."
In one of his rare speaking appearances, a visibly-frail looking King Tuheitia last week addressed his health issues at his koroneihana (coronation) celebrations held at Turangawaewae marae in Ngaruwahia.
"You are well aware of my personal fight with diabetes and cancer and I am pleased to report that these are being kept under control," he said at the time.
The Herald understands he underwent a gastric bypass last year after his doctors recommended he undertake the procedure.
It's understood that the King's family have maintained their vigil at his bedside.
Both they and the Kingitanga have asked for privacy.