Controlling blood glucose levels could reduce the risk of organ impairment in people with type 1 diabetes, according to a new study.
Swedish researchers explored the impact of HbA1c levels upon risks of diabetic retinopathy (eye disease) and nephropathy (kidney disease), analysing more than 10,000 adults and children with type 1 diabetes for between 8-20 years.
They discovered that, as expected, higher HbA1c levels were linked to increased signs of complications, but also warned of the dangers of people with type 1 diabetes keeping their HbA1c levels too low.
Those with type 1 diabetes whose HbA1c levels were above 70.5 mmol/mol (8.5%) had increased risks of damage to the eyes and kidneys compared with those who had HbA1c levels of 48-52 mmol/mol (6.5-6.9%).
Milder complications were observed among people whose HbA1c levels remained above 53 mmol/mol (7%). More severe complications mainly occurred in people with an HbA1c above 70 mmol/mol (8.6%).
The researchers identified that maintaining a value of 52 mmol/mol (6.9%) or below reduced the risk of organs being damaged. However, maintaining a value below 48 mmol/mol showed no further risk reduction.
“We were unable to see that fewer instances of organ damage occurred at these lower levels,” said co-lead author Professor Marcus Lind, from Sahlgrenska Academy, University of Gothenburg, and senior consultant at the NU Hospital Group in Uddevalla, Sweden.
“As for loss of consciousness and cramp, which are unusual, low blood glucose caused a 30% rise in risk. [People] with low HbA1c need to make sure they don’t have excessively low glucose levels, fluctuations or efforts in managing their diabetes.”
In Sweden, the HbA1c target is 52 mmol/mol or below, and 47 mmol/mol or lower in children. In the UK the target recommended HbA1c level for those with type 1 diabetes is 48 mmol/mol or below.
Professor Johnny Ludvigsson, from Linköping University, who also led the research, added: “Knowing more about the association between blood glucose level and risk is extremely important since the health care services, the community, patients and their parents make heavy use of resources in attaining a particular blood glucose level.
“Attaining a low HbA1c value may, in some cases, require children to be woken up several times a night, plus extra glucose monitoring and strict attention to diet and physical activity day after day, which can be extremely burdensome.”
The findings appear in The BMJ.