NHS Digital figures show just 24% of the 425 type 1 diabetes patients registered in the NHS Northumberland Clinical Commissioning Group area received all eight health checks in 2021 – down from 34% in 2019.
For the 8,090 type 2 patients, this figure rose to 38%, but was still down on pre-pandemic levels of 56%.
Nationally, just 26% of type 1 and 39% of type 2 patients completed the eight checks – respectively down from 31% and 50% in 2019.
Diabetes UK said missing health checks can be "absolutely devastating", potentially leading to life-altering complications and early death among the country’s five million people with the condition.
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Diabetics are expected to undergo eight annual health checks, including analysing their body mass index, smoking status, blood pressure and cholesterol.
NHS figures show more than 3,000 people with diabetes in England died during the pandemic due to the big drop in patients receiving annual check-ups.
Helen Kirrane, head of policy, campaigns and mobilisation at Diabetes UK the charity, said: "While the Government was focused on cutting waiting lists for operations and other planned care, people with diabetes were pushed to the back of the queue.
"Urgent action is now required."
A Department for Health and Social Care spokesperson said: "The NHS is supporting local systems with £36m in funding to help them increase uptake and tackle health inequalities, and last year, the number of diabetes patients receiving all eight care processes increased by nearly a third compared to the year before."