The effects of type 1 diabetes on cognitive performance: a meta-analysis.

Department of Neurology, University Medical Center, Utrecht, the Netherlands.
Diabetes Care (Impact Factor: 8.57). 04/2005; 28(3):726-35. DOI: 10.2337/diacare.28.3.726
Source: PubMed

ABSTRACT To investigate the exact nature and magnitude of cognitive impairments in patients with type 1 diabetes and the possible association with other disease variables, such as recurrent episodes of hypoglycemia and metabolic control.
MedLine and PsycLit search engines were used to identify studies on cognitive performance in patients with type 1 diabetes. Effect sizes (Cohen's d), which are the standardized differences between the experimental and the control group, were calculated. In the meta-analysis, a combined d value was calculated, expressing the magnitude of associations across studies.
A total of 33 studies were identified that met the inclusion criteria. Compared with nondiabetic control subjects, the type 1 diabetic group demonstrated a significantly lowered performance on the following cognitive domains: intelligence (d = -0.7), speed of information processing (d = -0.3), psychomotor efficiency (d = -0.6), visual (d = -0.4) and sustained attention (d = -0.3), cognitive flexibility (d = -0.5), and visual perception (d = -0.4). Lowered cognitive performance in diabetic patients appeared to be associated with the presence of microvascular complications but not with the occurrence of severe hypoglycemic episodes or with poor metabolic control.
In patients with type 1 diabetes, cognitive dysfunction is characterized by a slowing of mental speed and a diminished mental flexibility, whereas learning and memory are spared.The magnitude of the cognitive deficits is mild to moderate, but even mild forms of cognitive dysfunction might hamper everyday activities since they can be expected to present problems in more demanding situations.

1 Bookmark
  • [Show abstract] [Hide abstract]
    ABSTRACT: Diabetes is associated with macrovascular and microvascular complications and is a major risk factor for neurological and psychiatric disorders, such as dementia and depression. Type 1 diabetes (T1DM) and type 2 diabetes (T2DM) have distinct etiologies and pathophysiological effects while sharing a common endpoint of persistent hyperglycemia. Neuroimaging studies in T1DM have revealed reductions in numerous regions, including the parahippocampal and occipital regions, while in T2DM there have been numerous reports of hippocampal atrophy. This meta-analysis aimed to identify consistent regional abnormalities in cerebral structures in T1DM and T2DM respectively, and also to examine the impact of potential confounds, including age, depression and vascular risk factors. Neuroimaging studies of both voxel-based morphometry (VBM) data and volumetric data were included. Ten T1DM studies (n = 613 patients) and 23 T2DM studies (n = 1364 patients) fulfilled inclusion criteria. The T1DM meta-analysis revealed reduced bilateral thalamus grey matter density in adults. The T2DM meta-analysis revealed reduced global brain volume and regional atrophy in the hippocampi, basal ganglia, and orbitofrontal and occipital lobes. Moreover, hippocampal atrophy in T2DM was not modified by hypertension, although there were more marked reductions in younger patients relative to healthy controls. In conclusion, T1DM and T2DM demonstrated distinct cerebral effects with generalised and specific target areas of grey matter reduction. Thalamic atrophy in T1DM may be a substrate of associated cognitive deficits. In T2DM, global cerebral atrophy may reflect atherosclerotic factors, while hippocampal atrophy was an independent effect providing a potential common neuropathological etiology for the comorbidity of T2DM with dementia and depression.
    Brain Imaging and Behavior 01/2015; DOI:10.1007/s11682-014-9348-2 · 3.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We reviewed the evidence for the co-occurrence of type 1 diabetes mellitus (T1D) and multiple sclerosis (MS), and assessed the clinical significance of this association and the shared aetiological features of the two diseases. T1D and MS contribute considerably to the burden of autoimmune diseases in young adults. The co-occurrence of MS and T1D has been reported by a number of studies, suggesting that the two conditions share one or more aetiological components. Both conditions have been associated with distinct human leukocyte antigen (HLA) haplotypes but share a number of similarities in clinical, epidemiological and immunological features, leading to suggestions of possible common mechanisms of development. While underlying genetic factors may be important for the co-occurrence of both conditions, some evidence suggests that environmental factors such as vitamin D deficiency may also modulate an individual's risk for the development of both conditions. Evidence on whether the co-occurrence of the two autoimmune conditions will affect the disease course and severity of MS is merely absent. Further studies need to be conducted to ascertain whether the neuropathology associated with T1D might influence the disease course and contribute to the severity of MS. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of the Neurological Sciences 01/2015; 348(1-2):126-131. DOI:10.1016/j.jns.2014.11.019 · 2.26 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To study cognitive functions in 50–80 year aged type 2 diabetic patients. Cognitive performance was evaluated through a mini mental test (MMT) in 131 patients between 50 and 80 years (100 type 2 diabetics and 31 non-diabetics). Relation analysis were carried out for different parameters. Scores in registration and recall were significantly lower in diabetic group. The effect of HbA1c, body mass index (BMI) and age variables on MMT score was statistically significant. A negative linear correlation was estimated between MMT score and age, HbA1c level and BMI value. HbA1c, age and BMI were inversely related to cognitive functions. MMT scores were 24.98 ± 3.10 in diabetic group and 25.35 ± 3.22 in control group and statistically no significant difference was found. No significant difference was between type 2 diabetics and non-diabetics in terms of cognitive functions. But performance of diabetic patients in relation to the registration and recall was lower. Poor glycemic control and obesity in diabetics negatively affect cognitive performance.
    International Journal of Diabetes in Developing Countries 06/2013; 33(2):71-74. DOI:10.1007/s13410-013-0126-2 · 0.37 Impact Factor

Full-text (2 Sources)

Available from
May 29, 2014