Changes in HbA_1c and frequency of measuring HbA_1c and adjusting glucose-lowering medications in the 10 years following diagnosis of type 2 diabetes: a population-based study in the UK

The aim of this work was to study levels of HbA_1c and patterns of adjusting glucose-lowering drugs in patients with impaired glycaemic control over 10 years after diagnosis of type 2 diabetes.

We studied 4,529 individuals in The Health Improvement Network Database newly diagnosed with type 2 diabetes in the year 2000.

From 6 months to 10 years after diagnosis, the HbA_1c increased from 7.04% (53.4 mmol/mol) to 7.49% (58.3 mmol/mol) (average annual change: 0.047% [0.51 mmol/mol]). The greatest annual change occurred between 6 months and 2 years (0.21% [2.30 mmol/mol] increase per year, p < 0.001), followed by the 2–5 year time period (0.033% [0.36 mmol/mol] increase per year, p < 0.001). No significant increase in HbA_1c occurred between 5 and 10 years (p = 0.20). In multivariable analyses, patients who were younger (p < 0.001), with higher BMI (p = 0.033) and who were current insulin users (p = 0.024) at diagnosis had greater increases in HbA_1c between 6 months and 2 years. For individuals with HbA_1c above 7.0% (53 mmol/mol) the mean time to next measurement of HbA_1c was 0.53 years and increase in doses or changes to other glucose-lowering medications were performed in 26% of cases.

HbA_1c increases by approximately 0.5% (5 mmol/mol) over 10 years after diagnosis of type 2 diabetes, with the main increase appearing in the first years after diagnosis. More frequent monitoring of HbA_1c and adjustments of glucose-lowering drugs may be essential to prevent the decline.