Incidence Rate of Prediabetes: An Analysis of New Zealand Primary Care Data

Diabetes is a common disease affecting 9% of the adult population worldwide. People with impaired glucose tolerance ('prediabetes') are at high risk of progressing to type 2 diabetes.

To understand prediabetes incidence rate, we analysed the electronic medical records (EMR) from 14 New Zealand general practices regarding patients aged ≥20 years and enrolled with the practices between 2009 and 2012. Prediabetes incidence rate was calculated by the number of patients with an initial HbA1c of 41-49 mmol/mol in 2011 among those who had not been diagnosed or treated for diabetes.

28,192 adults were included in the analysis, 11% of this cohort had diabetes before 2011. 1,276 new cases of prediabetes were identified in 2011, giving a 5.0% incidence rate. The relative risk (RR) for prediabetes was increased for the Māori and Pacific groups versus non-Māori/non-Pacific people, with RR of 1.97 in the younger age groups (<50 years) and RR of 1.42 in the 50+ group. The RR for having uncontrolled HbA1c (highest HbA1c in 2011 ≥65 mmol/mol) among the whole adult population was also increased for the Māori and Pacific groups versus non-Māori/non-Pacific people (RR=3.35 among those <50 years, RR=4.35 in the 50+ group).

EMR analysis identified an alarming incidence rate of prediabetes, especially among Māori and Pacific groups, highlighting the need to better prevent and manage the condition.