The Ministry of Health may be identifying a significant number of New Zealanders as diabetic who do not actually have diabetes, an Otago study suggests.
The study of four Otago general practices - two rural and two urban - found 19% of those identified with the condition in the Ministry of Health's national data did not have diabetes.
Concern that only about half of Otago people with diabetes in 2008 appeared to have accessed their free annual check prompted the research, organised through the Otago Local Diabetes team, primary health organisations, the Otago District Health Board and the University of Otago Student Health Services.
The survey also highlighted issues with the recording of information in general practices.
Almost a third of those identified as not having accessed the Get Checked programme had done so, 9% had received checks which had not been recorded, and a further 10% had been treated at hospital level.
After making those adjustments, participation in the programme rose from 44% to 77%.
Local diabetes team co-chairman Prof Barry Taylor said if this finding was applied to Otago in general, he expected the overall amount of those receiving the annual free check was likely to be 70% or more.
However, ministry statistics suggested that last year only 53% of those with the condition in Otago accessed the free check.
The local diabetes team has called for the ministry to prioritise the development of an accurate method for determining the number of people with diabetes in New Zealand.
The ministry's data is based on appearance in any one of four national data sets - hospital discharge information, outpatient visits to specialist diabetes clinics, dispensing of oral hypoglycaemic agents or insulin, or four or more blood glucose tests (HbA1c) over a two-year period.
Prof Taylor said it had been assumed with the HbA1c tests that only diabetics would have that number of tests, but some doctors were ordering them regularly for patients who did not have the condition.
Similarly, some drugs were being used to treat severely overweight patients who did not have diabetes, medicines which had previously only been prescribed to those with diabetes.
Changes to calculations lowered the estimated number with the condition in Otago from 8704 to 8037 last year.
Prof Taylor said even if the real number was lower, it was still going to be "a lot of people" and there was " pretty clear" evidence the numbers were going up by about 5% a year.
