Type 1 diabetes is caused by antibodies attacking insulin-producing β-cells in the pancreas. Treatment is usually by regular insulin injections, informed by glucose measurements from fingerprick blood samples. However, injections do not mimic the normal behaviour of the β-cell and this leads to suboptimal blood glucose control and complications including kidney failure, blindness, nerve damage and heart disease. Aggressive treatment can help but may lead to potentially-dangerous low blood glucose levels (hypoglycaemia). Glucose control is measured by HbA1c (normal range 4 to 6%), a measure of the amount of haemoglobin exposed to glucose over a period of around 3 months.