Does Type 1 Diabetes at an Early Age Affect Brain Development?

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Influence of an early-onset age of type 1 diabetes on cerebral structure and cognitive function, by S.C. Ferguson and colleagues. Diabetes Care 28:1431–1437, 2005.

 

What is the problem and what is known about it so far?

According to previous studies, children who get type 1 diabetes at a very early age are more likely to score lower on intelligence tests (such as IQ and memory tests, among others) than their brothers or sisters who don’t have diabetes and those who get diabetes later in life. Some researchers think that the lower scores among children who get type 1 diabetes at a very early age might be a result of frequently high blood glucose levels, dangerously low blood glucose levels, or other physical conditions related to diabetes. Other researchers, however, think that the lower scores might be related to “psychosocial factors,” like lower attendance at school and behavior problems.

Why did the researchers do this particular study?

The researchers of this study wanted to see if the differences in thinking ability among children who get type 1 diabetes at a very early age might be related to differences in the structure of their brains. If differences in the structure of the brain are more common among children who get type 1 diabetes at an early age than among children who get diabetes later in life, then the development of diabetes at an early age might affect the development of the brain’s structure.

Who was studied?

Seventy-one young adults who had type 1 diabetes diagnosed during childhood or adolescence.

How was the study done?

Based on when the subjects were diagnosed with diabetes, 26 were put in the “early” group (they were diagnosed with type 1 diabetes before the age of 7) and 45 were put in the “later” group (they were diagnosed between 7 and 17 years of age). The participants took seven different tests to measure their thinking ability. They also underwent tests to scan the structure of their brains and to check for retinopathy (a form of diabetic eye disease). In addition, the participants filled out a questionnaire that asked about how many times and when they had extremely low blood glucose levels.

What did the researchers find?

The participants who were diagnosed before the age of 7 did worse on tests that measured intellectual ability and the ability to process information than those who were diagnosed between 7 and 17 years of age. In addition, abnormal brain structure was more common in the early group than in the later group.

What were the limitations of the study?

Previous studies have suggested that severe hypoglycemia, or dangerously low blood glucose, affects the development of the brain and can possibly cause brain damage in infants. In this study, the differences in the structure of the brain did not appear to be related to previous hypoglycemia, but the researchers relied on the participants’ responses to a questionnaire to record when and how many times they had dangerously low blood glucose levels. This isn’t a very reliable method.

What are the implications of the study?

The findings of this study indicate that differences in brain structure, intellectual ability, and the ability to process information are common in adults who developed type 1 diabetes before their 7th birthday. How these differences occur is still not clear; severe hypoglycemia at an early age may play a role. More studies are needed to confirm the findings of this study and to further explore how type 1 diabetes at an early age is related to the development of the brain.

FOR MORE INFORMATION

The effects of type 1 diabetes on cognitive performance: a meta-analysis, by A.M.A. Brands and colleagues. Diabetes Care 28:726-735, 2005.

Cognitive ability and brain structure in type 1 diabetes: relation to microangiopathy and preceding severe hypoglycemia, by S.C. Ferguson and colleagues. Diabetes 52: 149-156, 2003.