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

Introduction: 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.

Methods: Incident hypoglycaemia as recorded for the previous 10 years was determined from the GP records for patients with T2DM aged 75 years or more.

Results: 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.

Conclusion: 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.