Background Children with cancer, type 1 diabetes and other immune diseases often present initially with non-specific problems. It is unknown how long children with these conditions seek medical help before a diagnosis is reached.

Methods During the period 2002 to 2013, 7238 children aged 2–15 years diagnosed with cancer at seven sites, type 1 diabetes, and three other immune diseases were registered in the Taiwan National Health Insurance Catastrophic Illness Database. Their healthcare visit records in the year before diagnosis were extracted and compared to the records of matched controls during comparable periods using mixed-effect models.

Results Except for diabetes, there were substantial increases in healthcare visit rates in the last few months before a diagnosis of cancer or immune conditions, suggesting that some children had been seeking medical help and it had taken months to achieve a diagnosis. Many recorded presentations during this time were consistent with typical manifestations of the underlying condition, such as increasing apparent injuries before the diagnosis of bone cancer (6.6-fold increase in the most recent 4 months, 95% CI 4.9 to 9.0). Comparatively, healthcare visits in the year before the diagnosis of diabetes were less common, but at the time of diagnosis 64% (1504/2335) of children presented with diabetes ketoacidosis.

Conclusions Many children with cancer or immune diseases, even with typical presentations, required a period of time for the diagnosis to be confirmed. By contrast, children with type 1 diabetes typically did not visit a doctor until ketoacidosis had occurred.