Hypoglycaemia in older adults with diabetes
With an ageing population, it’s increasingly important to understand the impact of diabetes on older adults. Hypoglycaemia was the focus at the American Diabetes Association’s 83rd Scientific Sessions. Lisa Buckingham reports.
Continuous glucose monitors (CGM) may help identify older patients at high risk of hypoglycaemia – despite this, most studies do not include older participants, so CGM data in older populations is lacking, said Michael Fang, Assistant Professor in the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health. To address this, he and his colleagues aimed to assess the burden and major risk factors of CGM-detected hypoglycaemia in older adults with type 2 diabetes.
To do this, they used the Atherosclerosis Risk in Communities (ARIC) Study, an ongoing community cohort study, and took data from 2021-2022. Participants were aged between 77 and 93 and they studied the subset with type 2 diabetes (305 people).
All participants wore the Abbott FreeStyle Libre Pro. It measures glucose every 15 minutes and is worn for up to 14 days. It was a blinded device so glucose was not reported back to participants in real time. The primary measure they were interested in was CGM-detected hypoglycaemia and they defined this as the proportion of time glucose was below 70 mg/dL – current clinical guidelines suggest that older adults (with type 1 or type 2 diabetes) should spend less than 1% of time with glucose below this point.
They looked at four risk factors: diabetes (HbA1c, history of severe hypo); chronic conditions (heart and kidney disease); functional status (frailty and physical functioning), and cognition. Participants were divided into those who were on insulin and sulphonylureas (SU) and those who weren’t.
The first major finding, said Professor Fang, was that the majority had excessive CGM-detected hypoglycaemia. For those on no insulin/SU, about half were spending less than 1% of the time under 70 mg/dL and the other half were exceeding the threshold. For those on insulin/SU, two-thirds were exceeding the threshold. They also found that CGM-detected hypoglycaemia occurred mostly at night, specifically between the hours of 12am and 6am.
In the risk-factor analysis, they calculated the typical (median) amount of time people were spending below the threshold and then calculated that within the different clinical categories. The risk factor that came out first, he said, was medications – those using medications spent much more time under threshold. The second was cardiovascular disease – those with it spent much more time under threshold than those without; third was cognitive impairment and last was frailty. These associations persisted even after adjusting for age.
In sensitivity analyses, they looked at different thresholds (<60 mg/dL and 54 mg/dL) – at the lower thresholds, it was much less common to see CGM-detected hypoglycaemia, which suggests that most of the hypoglycaemia participants were experiencing was between the 70 mg/dL and 54 mg/dL range.
Strengths of the study, he said, include its community-based setting and limitations include the possibility of CGM error from factors such as compression lows (when you put pressure on your CGM, such as lying on it, it can give you a false low), CGM can be less accurate at low range and the Libre Pro may overestimate hypoglycaemia.
So, to conclude, in older patients with type 2 diabetes, CGM-detected hypoglycaemia is common, especially at night. Major risk factors include insulin or sulphonylureas, physical or cognitive impairment and cardiovascular disease. This suggests, he said, that we may need to implement more preventative strategies such as de-intensification, and CGM use may be beneficial for high-risk patients, especially those using insulin or sulphonylureas.
Severe hypoglycaemia among older adults with diabetes
Dr Alexandria Ratzki-Leewing, a diabetes epidemiologist at Western University, Canada, presented the latest results from the Investigating Novel Predictions of Hypoglycemia Occurrence Using Real-world Models (iNPHORM) study, an American prospective investigation of hypoglycaemia that looks at the incidence of hypoglycaemia among adults with diabetes.
She began with the definition of severe hypoglycaemia – a Level 3 low blood glucose concentration requiring third-party support (professional or non-professional) for recovery.
The impact on older adults is profound, she said, ranging from acute symptoms of comas, seizures, accidents and injuries to fear of hypoglycaemia, psychological and relationship impacts, increased risk of cognitive impairment and cardiovascular complications. All of this occurs in a bi-directional association that can contribute to frailty and ultimately increase risk of premature mortality.
Older adults in the US continue to be overtreated with insulin and sulphonylureas (more so than with younger adults) and, as a result, hypoglycaemia is the leading adverse drug event requiring hospital care.
There is a gap in the data on Level 3 hypoglycaemia occurrence among older adults, said Dr Ratzki-Leewing. Using data from the iNPHORM study, their aim was to quantify the real-world frequency of iatrogenic Level 3 hypoglycaemia among older, at-risk adults with diabetes living in the US.
The primary research design was a US-wide, 12-wave panel survey and data were collected on sample characteristics and Level 3 event frequencies. It included people with type 1 (10,000) or type 2 diabetes (58,000) between the ages of 18 and 90 years old. They had to be taking insulin or secretagogues.
From those broad criteria, this study specifically looked at those who were over 60 years old and had completed more than one follow-up. This was 307 individuals with either type of diabetes. The retention rate across the 12-month prospective period was 81.8%. About 8% had type 1 diabetes and 92% had type 2 diabetes and average age was 68. About half were female and the median diabetes duration was 16 years.
First, she characterised how Level 3 hypoglycaemia was reported in terms of the type of healthcare intervention that was required for recovery. Around 5% resulted in hospitalisation, emergency room visit or paramedic visit. The majority were treated at home by a family member or friend.
When looking specifically at the incidence proportion of Level 3 events (the proportion of individuals who reported having at least one severe hypo), they found that over the prospective period and across the total sample, about one in five reported having at least one Level 3 hypoglycaemia event. Unsurprisingly, more people with type 1 diabetes (42%) reported an event than those with type 2 diabetes (18%). She also drew attention to the fact that none of those with type 1 diabetes reported an event that required healthcare utilisation; it was those with type 2 diabetes that reported needing this.
Her key takeaways were as follows:
- This study was one of the first in the US to quantify real-world Level 3 hypoglycaemia among older adults using long-term, prospective data.
- Most (95%) events occurred outside the professional medical setting, underscoring the need for self-reported Level 3 event capture.
- Overall incidence estimates were greater in those with type 1 diabetes but healthcare utilisation was higher with type 2 diabetes.
- The benefits of tight glycaemic control need to be carefully weighed against the risk of hypoglycaemia in this especially vulnerable and growing population.
To learn more about hypoglycaemia in older people, enrol on the EASD e-Learning course ‘Hypoglycaemia’: https://easd-elearning.org/courses/hypoglycaemia/
Any opinions expressed in this article are the responsibility of the EASD e-Learning Programme Director, Dr Eleanor D Kennedy.