Aims To describe the prevalence of undiagnosed diabetes, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) (“dysglycaemia”) among Māori. Methods Te Wai o Rona: Diabetes Prevention Strategy was a trial of lifestyle change among Māori families in the Waikato/Lakes areas of New Zealand. All Māori family household members aged ≥28 years, without known diabetes, were invited to participate through primary care, community, and media approaches. Participants were invited to have an oral glucose tolerance test (OGTT). Results Of the 3817 eligible Māori, mean BMI was 32.9±7.8 kg/m2 (women) and 33.1±6.7 kg/m2 (men). The age standardised prevalence of undiagnosed diabetes was higher among men than women (6.5[5.8–7.4]% vs 4.2[3.6–4.8]%), as was that for IFG (5.4[4.7–6.1]% vs 3.0[2.3–3.5]%), but not IGT (8.5[7.6–9.4]% vs 9.7[8.7–10.6]%) with no rural-urban differences. The prevalence of dysglycaemia increased with increasing BMI with no clear inflection point and was 1.33(1.11–1.60) greater among those with a community services card after adjusting for age, sex and BMI. Conclusions Undiagnosed diabetes, IGT, and IFG remain common among Māori, particularly men, the very obese, and those with greater socioeconomic disadvantage. There remains significant opportunity to reduce Māori morbidity and premature mortality through diabetes case-finding and intervention.