Are elderly patients with diabetes at risk of hypoglycaemia when managed within the New Zealand guidelines for HbA1c?

Background
Hypoglycaemia in the elderly can significantly affect quality of life and independence, increase the risk of falls and is associated with increased mortality and length of stay in hospital. Guidelines in New Zealand are not age specific and recommend HbA1c levels are between 50 and 55mmols/mol for all people with diabetes. Achieving these targets for the elderly may increase the risk of hypoglycaemia, yet this risk can be overlooked by healthcare professionals as the person is assumed to have good glycaemic control. Recently a new electronic notification system was introduced which alerts the Diabetes Nurse Specialist (DNS) team when patients with diabetes are admitted to hospital. Since implementing this system the DNS team identified a number of elderly in-patients with HbA1c results of 55mmols/mol or below.

Aim
To identify elderly patients with diabetes who are at risk of hypoglycaemia in the in-patient setting. 

Method
An audit was undertaken for three months between October and December 2016 using a new notification system to identify patients with diabetes, 65 years and older admitted to hospital. Further data on those admitted was collected from the electronic clinical records including HbA1c, glucose lowering medication (excluding Metformin), any hypoglycaemic episodes and intervention by the DNS team. 

Results
Of the total admissions identified using the notification system (N=206), 34 patients (17%) were elderly (65 years or older), on one or more glucose lowering treatments: sulphonylurea (n=17), insulin (n=15), both (n=2), with an HbA1c 55mmols/mol or lower. One person was taking a thiazolidinedione. Of the total 26% had recorded or reported hypoglycaemia within the last month and 82% had been assessed by the DNS team as being at high risk of hypoglycaemia. Furthermore, 71% of patients had their insulin or oral glucose lowering medication reduced or stopped by the DNS team. 

Discussion
Results from this study demonstrate that a considerable proportion of elderly patients with diabetes on glucose lowering medication admitted to hospital in this period were experiencing, or were at risk of, hypoglycaemia. It is likely that the prompt intervention of the DNS team prevented and reduced further episodes in these patients. Healthcare providers need to be aware that underlying illness can increase the risk of hypoglycaemia in the elderly particularly if they are frail, malnourished, have long duration of diabetes or lose their ability to self-manage. It is also important to recognise that the current recommendations for HbA1c levels in this vulnerable population allow only a narrow margin of safety.