Being Overweight in Early Stages of Diabetes Linked to Brain Changes

A new study has found that patients with early stage type 2 diabetes (T2D) are more likely to have structural abnormalities in the brain and cognitive difficulties, particularly if they are overweight or obese.

Excess weight is a known risk factor for worsened glycemic and metabolic control in T2D, according to the study published in Diabetologia, but the researchers sought to investigate whether it could also play a role in cognition and brain structure. Study participants between ages 30 and 60 were separated into 3 groups: overweight or obese people with T2D, normal weight people with T2D, and normal weight people without diabetes.

Brain imaging of the participants revealed that the overweight T2D group had significantly lower mean cortical thickness than their normal weight counterparts. Specifically, there was the most thinning in the temporal cortex, which has been observed in patients with Alzheimer’s disease. The participants with T2D, regardless of weight, had thinner grey matter in several brain regions compared with the group without diabetes.

There also seemed to be a link between the length of time with diabetes and brain changes in overweight patients, as the integrity of the brain’s white matter was negatively correlated with disease duration in this group; this pattern was not observed in the T2D patients who were not overweight or obese.

The researchers also administered cognitive tests to assess the participants’ memory, psychomotor speed, and executive function. Regardless of weight, people with diabetes scored lower on these tests than those without diabetes. The overweight or obese patients with T2D showed diminished performance on the psychomotor speed tests related to their disease duration, while the normal weight T2D patients did not.

Additionally, the overweight or obese participants with T2D had higher mean glycated hemoglobin (A1C) levels at 7.3%, compared with a 7% average among those of normal weight. The American Diabetes Association advises people with diabetes to keep their A1C levels below 7%.

"Our findings also highlight the need for early intervention aimed to reduce risk factors for overweight or obesity in type 2 diabetic individuals to preserve their brain structure and cognitive function,” the study authors wrote. They emphasized the importance of insulin control in the early stages of T2D.

The researchers noted that their study population was Korean participants, so they could not say if the findings were applicable to other ethnic groups. They suggested that future studies might include overweight or obese patients without T2D to further clarify the link between diabetes, weight, and brain health.

"Further studies using a more elaborate framework are recommended to better describe the independent and combined (additive, synergistic or interactive) effects of T2D and obesity/overweight on the brain,” they stated.

Despite these limitations, the study authors indicated that the findings serve to emphasize the importance of weight control for patients with diabetes, particularly in the early stages of the disease.

"An increased awareness of overweight/obesity-related risk is necessary to prevent and manage type 2 diabetes-related brain atrophy and cognitive dysfunction from early stage T2D onward,” they concluded.