Abstract
ObjectiveWe aimed to investigate the alterations of brain functional connectivity (FC) in type 2 diabetes mellitus (T2DM) patients without clinical evidence of cognitive impairment and microvascular complications (woCIMC-T2DM) using resting-state functional MRI (rs-fMRI) and to determine whether its value was correlated with clinical indicators.MethodsA total of 27 T2DM and 26 healthy controls (HCs) were prospectively examined. Cognitive impairment was excluded using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA) scales, and microvascular complications were excluded by fundus photography, microalbuminuria, and other indicators. The correlation maps, derived from rs-fMRI with posterior cingulate cortex (PCC) as the seed, were compared between T2DM patients and HCs. Pearson’s correlation analysis was performed to determine the relationship between the FC of PCC and the clinical indicators.ResultsCompared with HC, woCIMC-T2DM patients showed significantly decreased FCs with PCC (PCC-FCs) in the anterior cingulate cortex (ACC), right superior frontal gyrus, right medial frontal gyrus, and right angular gyrus. Meanwhile, increased PCC-FCs was observed in the right superior temporal gyrus and calcarine fissure (CAL). The FC of PCC-ACC was negatively correlated with glycosylated hemoglobin (HbA1c) and diabetes duration, and the FC of PCC-CAL was significantly positively correlated with HbA1c and diabetes duration.ConclusionThe FC, especially of the PCC with cognitive and visual brain regions, was altered before clinically measurable cognitive impairment and microvascular complications occurred in T2DM patients. In addition, the FC of the PCC with cognitive and visual brain regions was correlated with HbA1c and diabetes duration. This indicates that clinicians should pay attention not only to blood glucose control but also to brain function changes before the occurrence of adverse complications, which is of great significance for the prevention of cognitive dysfunction and visual impairment.
Highlights
According to the prediction of the International Diabetes Association, the total number of diabetes patients worldwide will reach 642 million by 2040, of which type 2 diabetes mellitus (T2DM) accounts for 90%–95% [1]
No significant differences were identified in terms of age, sex, education level, body mass index (BMI), blood pressure, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), cerebrovascular disease, and cognitive functions between T2DM patients and healthy controls (HC), while fasting blood glucose (FBG) (11.43 ± 2.95 mmol/L) and HbA1c (8.74 ± 2.35%) in T2DM patients were significantly (p < 0.001 and p < 0.001, respectively) higher than those in HCs (3.83 ± 0.61 and 4.36 ± 0.29, respectively)
These regions included posterior cingulate cortex (PCC), the anterior cingulate cortex (ACC), precuneus, ventral medial prefrontal lobe, bilateral inferior parietal lobe, and angular gyrus, which were in line with the default mode network (DMN) regions [10]
Summary
According to the prediction of the International Diabetes Association, the total number of diabetes patients worldwide will reach 642 million by 2040, of which type 2 diabetes mellitus (T2DM) accounts for 90%–95% [1]. Brain morphological studies based on magnetic resonance imaging (MRI) have shown a reduction in gray matter density [3] and volume [4], a thinning of cortical thickness [5], and abnormal microstructure of the white matter [6] in T2DM patients compared with healthy controls (HC). These brain damages are not unique to diabetes, and occur in other diseases such as psychiatric disorders and mild cognitive impairment (MCI) [7]. Previous studies [9, 12] showed that the functional activity and the connectivity within the DMN in T2DM patients were abnormal compared with those in HCs
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