Dangerously low blood sugar (severe hypoglycaemia) has much more serious consequences in people who have both diabetes and dementia than those with diabetes alone, according to new research being presented at this year's European Association for the Study of Diabetes (EASD) Annual Meeting in Berlin, Germany (1-5 October).
The observational study found that, following hypoglycaemia, older adults with both diabetes and dementia were 67% more likely to die compared to those with diabetes alone.
"Hypoglycaemia is an under-recognised risk factor for death in older adults with diabetes and dementia", says Dr Katharina Mattishent (Alzheimer's Society Clinical Research Fellow) from Norwich Medical School, University of East Anglia, Norwich, UK who, under the supervision of Professor Yoon Loke, carried out the research. "Treatment strategies aimed at minimising hypoglycaemia should be prioritised in older patients with diabetes and dementia who are already prone to suffer from cardiovascular events, falls, and fractures."
A recent meta-analysis involving almost 1.5 million adults found that hypoglycaemia is linked with an increased risk of death, cardiovascular events, falls, and fractures. However, none of the studies examined these outcomes in specific groups of people at particularly high risk of hypoglycaemia, such as those with dementia and diabetes.
To investigate this further, Mattishent and colleagues analysed data from 19,995 patients with type 1 or type 2 diabetes aged 65 years or older both with and without dementia who were diagnosed with the first hypoglycaemic episode between April 1997 and 31 March 2016. The study was carried out using the UK Clinical Practice Research Datalink (CPRD), the world's largest primary care database, and data on hospital admission from the Hospital Episode Statistics (HES).
The researchers followed participants for up to 5 years after their first recorded hypoglycaemic episode to examine whether hypoglycemic episodes were associated with death from any cause in patients with dementia and diabetes, and whether hypoglycemic episodes had a different impact on mortality in diabetics with and without dementia. The results were adjusted for influential factors including age, sex, sociodemographics, comorbidities, and medications. Over the study period, 11,716 people died from any cause.
Following hypoglycaemia, patients with diabetes and dementia had a 66% greater risk of death as those who did not experience hypoglycaemia (1369 deaths/1679 patients vs 3853 deaths/6134 patients).
The analysis also found that, following hypoglycaemia, diabetics with dementia were 66% more likely to die as those without dementia (1369 deaths/1679 patients vs 6494 deaths/12182 patients).
Dr Mattishent concludes, "Given the continuous rise in diabetes and dementia prevalence and the ageing population, strategies to prevent and reduce hypoglycaemia in older people with dementia and diabetes must be a top priority."
"In this vulnerable group, clinicians and patients should move away from relentless pursuit of strict glucose-lowering targets. The focus must be directed at rigorous detection of hypoglycemia using continuous glucose monitoring devices. This close monitoring will guide treatment choices with regards to drugs that have a low risk of hypoglycemia in this patient group."
Commenting on the study, Dr James Pickett, Head of Research at Alzheimer's Society, said: "With no new dementia drugs in 15 years, minimising risk and improving care is key. We know that diabetes can raise the risk of developing dementia, and with both of these illnesses on the rise we urgently need to understand this relationship better."
"Very low blood sugar levels are clearly dangerous to anyone with diabetes, and this suggests the effects might be even more extreme in people with dementia. The study didn't show cause and effect but, given the dangers of low blood sugar levels, clearly it should be managed carefully. As well as this study, Alzheimer's Society is currently funding nearly one million pounds worth of research into links between diabetes and dementia."
This is an observational study, so no firm conclusions can be drawn about cause and effect and the authors point to several limitations. First, the databases may not have captured all hypoglycaemia events. Furthermore, lifestyle factors, such as smoking, exercise and alcohol use may not have been reliably entered on the database. Finally, the CPRD database does not specify the severity of dementia and the authors are therefore not able to assess whether the risks are worse with severe dementia.