الفهرس 
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Abstract
Diabetes mellitus describes a metabolic disorder of multiple aetiology characterized by chronic hyperglycaemia with disturbances of carbohydrate, fat and protein metabolism resulting from defects in insulin secretion, insulin action, or both. The effects of diabetes mellitus include long-term damage, dysfunction and failure of various organs.
Expert Committee proposed two major classes of diabetes mellitus and named them, IDDM or Type 1 (beta-cell destruction, usually leading to absolute insulin deficiency), and NIDDM or Type 2. (may range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with or without insulin resistance).
The diagnosis of diabetes is based on one of three methods of blood glucose measurement .Diabetes can be diagnosed if the patient has a fasting blood glucose level of 126 mg per dL (7.0 mmol per L) or greater on two separate occasions. The limitations of this test include the need for an eight-hour fast before the blood draw, a 12 to 15 percent day-to-day variance in fasting blood glucose values, and a slightly lower sensitivity for predicting microvascular complications.
An HbA1c of 48 mmol/mol (6.5%) is recommended as the cut point for diagnosing diabetes. A value of less than 48 mmol/mol (6.5%) does not exclude diabetes diagnosed using glucose tests.
The complications of diabetes mellitus are far less common and less severe in people who have well-controlled blood sugar levels, which are acute and chronic complications affecting most body systems.
A less addressed and not as well recognized complication of diabetes is cognitive dysfunction. Patients with type 1 and type 2 diabetes mellitus have been found to have cognitive deficits that can be attributed to their disease. Both hypoglycemia and hyperglycemia have been implicated as causes of cognitive dysfunction, and many patients fear that recurrent hypoglycemia will impair their memory over time. Although much research has been done, the pathophysiology underlying this complication is not well understood, and the most appropriate methods to diagnose, treat, and prevent cognitive dysfunction in diabetes have not yet been defined.
In this study a comprehensive review of the literature regarding the subject of cognitive dysfunction was presented.It must be remembered that although there have been many significant contributions regarding the association of diabetes and cognitive dysfunction and many hypotheses based on this association, the causative mechanisms of diabetes on cognitive dysfunction are still undergoing development.
Glycaemic control appears to play a role in determining the degree of cognitive dysfunction detected in patients with type 2 diabetes, although this has not uniformly been observed.
In patients with type 1 diabetes mellitus, deficits in speed of information processing, psychomotor efficiency, attention, mental flexibility, and visual perception seem to be present, whereas in patients with type 2 diabetes, an increase in memory deficits, a reduction in psychomotor speed, and reduced frontal lobe/executive function have been identified. Severe hypoglycemic episodes may contribute to cognitive dysfunction in the young; however, as patients age episodes seem to have less of an influence.
We have studied 40 patients of young and middle age group in MUST university hospital, of age range (20-50), they were 21 male patients and 19 female patients, all are having Diabetes mellitus for a period ranging from 5-35 years. According to their presentation (20) patient having a diagnosis of type 1 DM and (20) patients having type 2 DM. they were kept on their therapeutic medications.
All were submitted to the following:
1- Proper history taking , general and neurological examinations.
2- Blood pressure measurement.
3- Body mass index measurement.
4- Laboratory investigations which is fasting blood glucose and Hb A1c.
5- Radiological investigation:
Which is CT brain without contrast was done
6- Neuropsychological assessment: we use the following neuropsychological battery: Minimental state examination (MMSE) ,Wechsler scale for memory and Hamilton scale for depression .
Patients were assigned to one of the two groups, depending on the type of diabetes. One group (A) which is type 1 and the other group (B) which is type 2 DM.
The study had the following results:
Our studied group were of age mean+ SD ( 38.8+9.87 ), they were 52 % male , and 48 % female diabetic patients they were recruited from MUST university hospitals.
Regarding associated diseases: 25% of type1 and 50% of type 2 having hypertension, 35% and 10% out of type 2 having cardiac disease as well as thyroid respectively.
When we compare the clinical course of diabetes in both groups we found:
As regards age of onset of DM, 20 patients with type 1 DM have mean age 15 years (range = 13.5- 18.5) and 20 patients with type 2 DM have mean age 30.5 years (range = 30- 35.5). And duration of DM in both types, 20 patients with type 1 DM have mean duration 13.5 years (range = 10- 26.5) and 20 patients with type 2 DM have mean duration 10 years (range = 7.5- 14).
In type 1 DM 90% of patients treated with insulin, 10% treated with oral hypoglycemic drugs and 25% uncontrolled. While in type 2 DM 15% treated with insulin, 85% treated with oral hypoglycemic drugs and 65% uncontrolled.
Regarding the complications of DM, we found that:
1- Diabetic coma
In type 1 DM: 10% exposed to coma thrice, 15% twice, 15% once and the remaining not exposed. In type 2 DM: 20% exposed to coma thrice, 20% twice and the remaining not exposed
2- Diabetic neuropathy
70% of type 1 DM and 55% of type 2 DM.
3- Diabetic retinopathy
25% of type 1 DM and 25% of type 2 DM.
4- Diabetic nephropathy
5% of type 1 and 5% of type 2 DM.
5- Diabetic foot
45% of type 1 and 50% of type 2 DM.
6- TIA
55% of type 1 and 25% of type 2 DM.
7- Sphincteric dysfunction
15% of type 1 and 25% of type 2 DM.
When we compare the clinical examination in both groups we found:
1- As regards arterial blood pressure of patients with DM, 20 patients with type 1 DM have mean systolic blood pressure 130 mmhg (range = 120- 140) and 20 patients with type 2 DM have mean systolic blood pressure 135 mmhg (range = 130- 150).
2- Neurological examination:
We found that 60% of type 1 and type 2 are normal.
*25% type 1 and 35% type 2 had numbness.
*10% type 1 and 5% type 2 had facial palsy.
*5% type 1 and 0% type 2 had lower limb hyposthesia.
*25% type 1 and 20% type 2 had papilledema on fundus examination.
About the results of laboratory and radiological investigations in both study groups we found that:
1- 20 patients with type 1 DM have the mean fasting blood sugar 238.1; while it is 276.15 in patients with type 2 DM.
2- 20 patients with type 1 DM have the mean HbA1c 5.75 (range=5.3-8.0); while it is 7.65(6.5 – 9.6) in patients with type 2 DM.
Psychometric evaluation of cognitive functions in our diabetic patients
When we assess our patients by different scales we found that:
1- Mini mental state examination: 20 patients with type 1 DM have mean MMSE score 25.5(range = 22-28) and 20 patients with type 2 DM have mean MMSE score 24 (range= 22- 26).
*In type 1 DM 60% are normal cognitive functions, 40% mild and 0% moderate cognitive impairment.
*In type 2 DM 40% are normal, 55% mild and 5% moderate cognitive impairment.
2- Hamilton scale: 20 patients with type1 DM have mean Hamilton score 12(range = 5.5 – 20) and the 20 patients with type 2 DM have mean Hamilton score 16(range = 10- 21.5).
*In type 1 40% are normal, 30% below normal ,10% mild and 20% moderate depression.
*In type 2 20% are normal, 35% below normal, 30% mild and 15% moderate depression
3-Wechsler memory scale
The prevalence of impaired memory as per the Wechsler memory score (WMS) in both study groups:
*In type 1 DM :
a- Associate learning: 95% are impaired memory.
b- Digit span backward: 30% impaired.
c- Digit span forward: 75% impaired.
d- Logical memory: 40% impaired.
e- Mental control: 95% impaired.
f- Orientation and information: normal.
In type 2 DM:
a- Associate learning: 95% are impaired memory.
B- Digit span backward: 40% impaired.
C- Digit span forward: 90% impaired.
d- Logical memory: 50% impaired.
E- Mental control: 90% impaired.
f- Orientation and information 100% normal
Correlations between cognitive dysfunction and glycemic control as measured by Hb A1C
Of the 40 patients were involved in the study, 20 patients have normal cognitive function with mean HbA1c 7.3 (range= 5.4 – 9.2), 19 patients have mild cognitive impairment with mean HbA1c 6.5 (range= 5.7 – 8.1) and only 1 patient has moderate cognitive impairment with mean HbA1c 6.5 (range= 6.5 – 6.5)
Of the 40 patients were involved in the study, 12 patients have normal mood with mean HbA1c 6.6 (range= 5.6 – 8.5), 13 patients have below normal depression with mean HbA1c 7.14 (5.3 – 8.2) and 8 patients have mild depression with mean HbA1c 7.2 (6.1 – 9.4). 7 patients have moderate depression with mean HbA1c 6.5 (range= 5.9 – 12.3).
38 patients have impaired associate learning with mean HbA1c 6.7 (range= 5.7 – 8.8) and 2 patients have normal associate learning with mean HbA1c 6.2 (4.1 – 8.4). 14 patients have impaired digit span (backward) with mean HbA1c 6.6 (range= 5.8 – 8.5) and 26 patients have normal digit span (backward) with mean HbA1c 6.92 (5.3 – 8.8).
33 patients have impaired digit span (forward) with mean HbA1c 7.3 (range= 5.8 – 9.5) and 7 patients have normal digit span (forward) with mean HbA1c 5.68 (5.1 – 6.5).
18 patients have impaired logical memory with mean HbA1c 6.6 (range= 5.8 – 10.1) and 22 patients have normal logical memory with mean HbA1c 6.92 (5.3 – 8.1)
37 patients have impaired mental control with mean HbA1c 6.7 (range = 5.6 – 8.6) and 3 patients have normal mental control with mean HbA1c 8.38 (range = 6.3 – 9.3).
40 patients have normal orientation and information with mean HbA1c 6.7 (range = 5.7 – 8.7)
Gender difference and Cognitive impairment
1- MMSE scoring,
A- Of the 21 male patients were included in the study,
* (52.4%) have mild cognitive impairment.
* (47.6%) have normal cognitive function.
B- Of the 19 female patients were included in the study,
* (42.1%) have mild cognitive impairment,
*(5.3%) have moderate cognitive impairment.
*(52.6%) have normal cognitive functions.
2-Hamilton scoring,
A- of the 21 male patients were included in the study:
*28.6% have normal mood
*28.6% have below normal depression,
*33.3% have mild depression and
*9.5% have moderate depression.
B- Of the 19 female patients were included in the study:
*31.6% have normal mood
*36.8% have below normal depression,
*5.3% has mild depression and
*26.3% have moderate depression.
3-Wechsler scoring,
A- of the 21 male patients were included in the study,
* 95.2% have impaired associate learning and
* 33.3%have impaired digit span (backward) and
*85.7% have impaired digit span (forward) and
*38.1% have impaired logical memory and
*90.5% have impaired mental control and
*100%have normal orientation and information.
B- Of the 19 female patients were included in the study,
*94.7% have impaired associate learning an
*36.8% have impaired digit span (backward) and
*78.9% have impaired digit span (forward) and
*52.6% have impaired logical memory an
*94.7% have impaired mental control an
*100% have normal orientation and information
Conclusion
In conclusion, there have been significant gains in our understanding of the effect of diabetes on cognitive dysfunction. Evidence from neurocognitive testing suggests that cognitive dysfunction should be listed as one of the many complications of diabetes, along with retinopathy, neuropathy, nephropathy, and cardiovascular disease. The pathogenesis of cognitive dysfunction is only partially understood. Although many studies suggest that changes in cerebral structure and function in diabetes are related to hyperglycemia-induced end organ damage, macrovascular disease, hypoglycemia, insulin resistance, and amyloid lesions may play a role in some patients.
Young and middle aged diabetic patients have the risk of undiagnosed cognitive dysfunction, neuropsychological tests have shown various cognitive impairement in diverse scales, as mild cognitive impairement, depression , memory problems, associate learning, digit span forward, logical memory and mental control.
Considering the importance of self-management behaviors in diabetes treatment and the high complexity of diabetes treatment regimens (e.g., blood glucose testing, meal planning, and medication compliance), diabetic patients with cognitive dysfunction may experience significant difficulty in managing their disease.
Greater understanding of the natural history of this diabetes complication and the mechanisms responsible for its development will continue to advance as biochemical and imaging modalities continue to evolve. As new knowledge is gained, it can be applied to develop new and improved ways to prevent and treat all of the hyperglycemia-related complications of diabetes