الفهرس 
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Abstract
Type 1 Diabetes Mellitus (T1DM) is one of the most common chronic illnesses that affect children under the age of 18 and in young adults . There has been interest in the neurocognitive dysfunction of individuals with T1DM due in part to the possibility of metabolic abnormalities that might affect brain functions as well as clinical observations of diminished mental capacity and evidence of electroencephalogram abnormalities associated with extreme hyperglycemia.
The brain uses glucose, largely through oxidative metabolism, as its primary fuel for energy generation. Hypoglycemia can occur as a result of excessive insulin intake, excessive exercise or consumption of foods considered inappropriate for the diabetic’s diet When blood glucose levels are reduced to levels below ~ 3 mmol/l, subtle brain dysfunction occurs in humans within minutes, Metabolism of glucose non-oxidatively to lactate also occurs in brain and may be important for rapid responses to synaptic activity, There are also new conceptual insights into how glycogen helps the brain deal with rapidly changing metabolic circumstances and defend against hypoglycemia
Early onset of diabetes may result in later cognitive problems for two reasons. First, the central nervous system may be affected at a critical period of development as a result of changes in hormone levels and other physical changes associated with the onset of the disease ,especially to who acquire the disease before they are 5-years old. A second potential reason is the fact that onset of the disease at an early developmental period may result in poorer metabolic control of a child’s diabetes while the child is still young. This may lead to more frequent episodes of low or high blood sugar, which has been linked to deficits in cognitive functioning
Brain studies have shown that humans who experienced severe hypoglycemic episodes have areas of cortical necrosis in the frontal lobes and hippocampus, which are the primary brain structures associated with memory functions with relative sparing of the hindbrain
Deficits in cognitive function have been detected as early as 2 yr after diagnosis in children with type 1 diabetes, and these patients experienced less positive changes than controls over time in general intelligence, vocabulary, block design, speed of processing, and learning .
Six years after diagnosis, these same subjects had impaired IQ, attention, processing speed, long-term memory, and executive function compared with controls.
The most common cognitive deficits identified in patients with type 1 diabetes are slowing of information processing speed and worsening psychomotor efficiency. However,other deficits have been noted, including deficits in motor speed , vocabulary , general intelligence ,visuoconstruction,attention , somatosensory examination, motor strength , memory ,and executive function .
some studies were believe that there is a relationship between impaired cognitive function and diabetic complications ,other were unable to find link between them
also,some studies found that Patient gender influence neurocognitive function as Decline in verbal intelligence was seen in boys with type 1 diabetes between the ages of 7 and 16, which correlated with worse glycemic control. This was not seen in girls of similar ages
Boys have been found to have a higher risk for neuropsychiatric disorders and learning disabilities because the central nervous system develops at a slower rate for males than for females
Because of the limitations in neurocognitive testing, a number of modalities have been used to assess cognitive function in patients with diabetes as Neurocognitive testing , Evoked response potentials, EEG, MRI ,fMRI ,PET ,SPECT.