There were a total of 6,301 no-show face-to-face consultations with doctors and nurses over the course of the month, NHS Digital data shows.
Across England, the average cost of an appointment is £30, meaning no-shows in Sunderland cost the NHS an estimated £189,000 over the month – equivalent to the annual salary of eight full-time nurses.
And with sessions usually lasting around 10 minutes, unattended appointments meant GPs and other practice staff wasted 1,050 hours of consulting time.
David Gallagher, chief officer of NHS Sunderland Clinical Commissioning Group (CCG) said: “There are many genuine reasons why people may need to cancel or reschedule an appointment, but it is important that people let their GP practice know if they are unable to attend.
UPDATE: Part of Wessington Way remains closed and repairs underway after burst pipe causes travel chaos
Fundraiser to be held in memory of Sunderland businessman who died following 'freak accident'
'Like a steam roller' - watch workers describe 'scary' scenes as reports of ground tremors and houses shaking lead to evacuations
Dad of Sunderland AFC fan who took his own life appeals for donations of football equipment as he prepares to launch charity in son's name
Firefighters ramp down operation after large allotment fire in Easington Lane
“GP appointments are in great demand, and by simply not turning up you are making it harder for other patients to be seen.
“Missed appointments also cost the NHS a lot of money.
“We all have a responsibility to make the best use of NHS resources and this includes appointments at the GP practice.
“If you have an appointment coming up that you no longer need or are unable to attend, please let your practice know as soon as possible.”
In December, a total of 92,605 face-to-face consultations were booked with GPs and other practice staff in the Sunderland Clinical Commissioning Group.
Of them, one in 15 was missed without the patient calling in to cancel or reschedule.
Cancelled appointments are not included in the figures, as the surgery can offer those slots to other patients.
The Royal College of GPs (RCGP) said missed sessions are “a frustrating waste of resources” for GPs, and other patients struggling to secure time with their doctors.
According to the RCGP, practices nationwide are increasingly using electronic methods, such as text reminders, to encourage patients to keep appointments or cancel them in plenty of time.
RCGP chair Professor Helen Stokes-Lampard said: “We would urge patients to let us know if they can’t attend appointments as soon as possible, so we can offer that time to someone who really needs it.
“Many patients are waiting far too long for a GP appointment, and we can all do our bit to help.”
More than a million patients failed to attend appointments in England in December, racking up estimated costs of more than £30million.
The British Medical Association said it was vital that appointments were not wasted at a time of intense pressure on the NHS.
The association’s GP committee chair, Dr Richard Vautrey said: “We believe that the NHS should make clear to the public that, given current pressures on the health service, patients should make every possible effort to attend or rearrange their appointment to avoid time and money being wasted.”
NHS England has urged patients to do their part to cut down on missed appointments.
Primary Care director Dr Nikki Kanani said: “Our message is clear: if you cannot make it to your appointment, or no longer need a consultation, please let your practice know in advance.”