Discover diabetes: screening for diabetes mellitus in the Waikato

Free screening for diabetes mellitus was offered, in three rural communities as part of an initiative of the Waikato Area Health Board to improve the detection and management of type 2 diabetes.

An organised campaign promoted glucose testing as an important preventative health measure for 'at risk' members of the community. At risk was defined as being either Maori over 20 years of age, European over 40 years of age, obese or having a family history of diabetes. The testing method was a random capillary glucose test followed by an oral glucose tolerance test for those with a result > or = 8 mmol/L.

Five thousand five hundred and eighty nine people voluntarily attended screening at various sites. Sixty of these people were already known to have diabetes and were subsequently excluded. One thousand and four people had no recognised risk factors. Four thousand five hundred and twenty one people with risk factors for type 2 diabetes had a capillary blood glucose test and 162 were found to have a capillary glucose greater than 8 mmol/L. Four patients did not have their glucose result recorded. One hundred and forty one oral glucose tolerance tests were performed and 56 new patients with diabetes were identified based on WHO criteria for diabetes. The prevalence of previously undiagnosed diabetes was higher in those over 50 years of age, particularly if they were Maori. It was also higher in obese Maori in the 30-49 year age group.

Although over 5000 patients attended screening, this testing included only 34% of the at risk age group. Thus voluntary testing, despite a major investment in promotion, proved ineffective as a population screening tool. A random capillary glucose test proved to be a simple and sensitive method of helping to identify previously undiagnosed disease. This could be effectively used by general practitioners, targeting all adults over 50 years of age, and all adult Maori with obesity as defined by a BMI > or = 30.