Diabetes. Hyperglycemia increases the risk of dementia.

By Anne Prigent – ​​Le Figaro

Diabetes, known to increase the risk of heart attack, vision problems, stroke, and kidney failure, may also play a role in the development of dementias, including Alzheimer's disease, especially in people whose blood glucose levels are not properly controlled.

In these latter cases, the risk of dementia is 50% higher than in diabetics with good glycemic control, as shown by a study presented at the last diabetology congress in Stockholm. To reach this result, researchers at the Gothenburg Institute in Sweden monitored more than 350 diabetics over the age of 50 and without dementia at the time of their inclusion in the study for eight years. These patients were followed until death, their hospital admission for dementia, or the end of the study in 2012. The authors attempted to explore the association between disease "control," glycated hemoglobin levels, and the risk of hospitalization for dementia in people with type 2 diabetes.

Link between hyperglycemia and cognitive disorders

Glycated hemoglobin concentration, which assesses the average blood sugar level over the past three months, provides information about the quality of glycemic balance. It is a retrospective index, in contrast to blood glucose levels which provide a result valid for the day of collection. In total, 13.159 dementia events were observed in an average monitoring period of 4,8 years. And patients with a glycated hemoglobin of 10,5% or higher were 50% more likely to be hospitalized for dementia than those with a glycated hemoglobin level of 6,5%. "The brain depends on glucose to function and does not produce it, so it is not surprising that there is a link between hyperglycemia and cognitive disorders," explains Prof. Lyse Bordier, diabetologist at the Bégin Hospital in Saint-Mandé.

Over time, hyperglycemia will cause microangiopathy, meaning it will weaken the walls of the small blood vessels that supply tissues with oxygen and nutrients, resulting in cognitive impairment and increasing the risk of dementia.

Does this mean it's possible to prevent dementia in diabetics by strictly controlling blood glucose? Lyse Bordier remains cautious: "This study demonstrates that when diabetes is poorly controlled, the risks of dementia increase, but it doesn't address all the complex parameters involved in the onset of cognitive disorders in diabetics. Especially the deleterious role of hypoglycemia," the specialist points out. Furthermore, the people at highest risk of developing dementia in the Swedish study had a particularly high glycated hemoglobin level.

In France, less than one in ten diabetics has reached this 10% rate, according to the Entred study conducted by the Health Insurance company, and the average level is 7,1%. However, it's worth noting that only 30% of diabetics achieve a maximum glycemic balance below 6,5%. "But this maximum target doesn't mean much: it must be individualized according to the patient. We will be much more ambitious with a forty-year-old who has just been diagnosed than with an 85-year-old with several pathologies," says Lyse Bordier.