Auckland District Health Board says it appears a variety of missed opportunities was involved in the death of a woman with insulin-dependent diabetes.
The 68-year-old died in September of hypoglycaemia, or abnormally low blood sugar levels, and the district health board ordered an independent review.
The report says the sequence of events suggests opportunities to review her treatment and prevent the hypoglycaemia may have been missed.
Auckland District Health Board identifies many points where things could have been better managed and recommends that new lab-testing firm Labtests, the woman's doctor and the St John Ambulance all consider making changes.
Labtests says changes recommended in the report have been made.
Auckland District Health Board acting chief medical officer, Margaret Wilshir, says no single action or group can be blamed.
"Our investigation demonstrates, with hindsight, some possible opportunities for intervention, which if carried out might have prevented the outcome.
"But I think we need to be aware that patients who require insulin for their diabetic control do walk a tightrope - hypoglycaemic events are common and sometimes they are lethal."