We often think of ageing in terms of what we can do aesthetically — we might do the odd bit of needlework, pop on an LED mask before bed, or slather skin with the latest retinol-infused moisturiser.

The haemoglobin glycation index (HGI) represents the difference between measured glycated haemoglobin (HbA1c) and values predicted from blood glucose levels. This quantitative marker offers insights ...