Hypoglycaemia in the over 75s: Understanding the predisposing factors in type 2 diabetes (T2DM).

Abstract

Hypoglycaemia has been recognised as a problem in the treatment for type 2 diabetes. Here we describe how levels of HbA1C and treatment with a sulphonylurea or insulin relate to risk of significant hypoglycaemia. Incident hypoglycaemia as recorded for the previous 10 years was determined from the GP records for patients with T2DM aged 75 years or more. The anonymised GP records of 5974 T2DM patients (2934 men and 3040 women) aged 75 years or more were analysed. Mean age of the men was 81.0 (95% confidence interval (CI) 80.9-81.2) years and of the women was 82.2 (95% CI 82.0-82.4) years. Hypoglycaemic events of significance were recorded in 4.9% of men and 5.1% of women. The prevalence of hypoglycaemia was higher in those with a higher concurrent HbA1C. HbA1C for those people with a recorded significant hypoglycaemic attack(s) was 57.9 (95% CI 56.4-59.4) mmol/mol compared to those with no history of hypoglycaemic episodes at 51.6 (95% CI 51.3-52.0) mmol/mol (p<0.002). Even for those on sulphonylurea and/or insulin treatment, hypoglycaemia prevalence increased with HbA1C: for patients with an HbA1C of <48mmol/mol, age and gender adjusted hypoglycaemia prevalence was 11.1%, for HbA1C of 48-57mmol/mol, prevalence 9.9%, for HbA1C 58-67mmol/mol prevalence, 13.2% and for HbA1C 68mmol/mol or more, prevalence of hypoglycaemia was 16.1%. There was a slight fall in HbA1C by age (normalised β -0.069, p<0.001) and no difference by level of social disadvantage. Treatment with a sulphonylurea or insulin very significantly increased the likelihood of a hypoglycaemic episode: odds ratio (OR) 8.94 (95% CI 6.45-12.42), p<0.001, independent of age, BMI, Townsend index and gender. Prevalence of hypoglycaemia was greater in those individuals with higher HbA1C and in those on sulphonylurea/insulin treatment. Our findings suggest that it is variance in blood glucose rather than overall lower blood glucose levels that predisposes older people to hypoglycaemia.