This study determined risk factors monitored in primary care that were significantly associated with diabetes complications requiring hospitalisation, using clinical and demographic data for 1080 type 1 and 11,283 type 2 New Zealand diabetes patients attending a free primary care diabetes examination between 2000 and 2002. Hospital admissions data for the 2 years following the index examination were linked for each patient using a unique National Health Index code. Hospitalisations for diabetes complications occurred in 222 cases (20.6%) in the type 1 cohort and in 1948 cases (17.3%) in the type 2 cohort. In both cohorts, patients admitted with diabetes complications had significantly higher mean glycosylated haemoglobin (HbA1c) and triglyceride levels, urine albumin:creatinine ratios and duration of diabetes than patients not admitted. In type 2 patients, age, obesity, HbA1c, urine albumin:creatinine ratios, HDL levels and treatment with insulin or oral medication increased the likelihood of admission.