Prevalence Of And Risk Factors For Dementia In Diabetics: A Community-based Case-control Study

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia, caused by insufficient production of insulin and resulting in abnormal metabolism of carbohydrates,fats,and proteins.Long-term diabetes mellitus can cause cerebral vascular disease,even vascular dementia.Some fundamental studies have proposed that diabetes mellitus might give rise to Alzheimer's disease.A great amount of epidemiology research has reported that diabetes mellitus is positively associated wtih dementia.The purpose of this project is to study the prevalence of and risk factors for dementia in diabetics by carrying out a community-based case-control study.Part One Prevalence of Dementia in Diabetics:A Community-based SurveyObjectives:To determine prevalence of dementia in diabetics and non-diabetics,and in different age and gender groups.To estimate prevalence of dementia in diabetics in different duration,therapy,complication and control condition groups.Methods:A case-control study was conducted among participants aged 40 and over in Jing'an temple community of Shanghai.Both the diabetic group and non-diabetic group were classified by case history,self-report,blood glucose test and HbA_1C.Personal information and case history were collected through questionnaire.The subjects were screened for dementia using the Mini Mental State Examination(MMSE).Subjects that screened positively(indicated by an MMSE score below 19,21 and 24 among those with illiteracy,elementary school and above junior middle school education,respectively) were subsequently examined by a series of neuropsychological tests.Based on all available information,a diagnosis of dementia was defined according to DSM-â…£criteria.Results:1025 subjects were recruited in the study(diabetic group:n=512, non-diabetic group:n=513).Prevalence of dementia in diabetics(4.45%) was higher than that in non-diabetics(2.00%)(P=0.028).Prevalence of dementia among age groups 60-69, 70-79 and 80 and above in diabetics was 1.94%,4.95%and 12.20%,and in non-diabetics was 0.00%,3.35%and 5.00%,respectively.Prevalence of dementia among female and male in diabetics was 6.42%and 1.52%(P=0.010),respectively,and in non-diabetics was 2.93%and 0.52%(P=0.097),respectively.Prevalence of dementia in diabetics among different duration,therapy,complication and control condition groups are listed as follows:"5 years and under" and "over 5 years" duration was 3.83%and 4.91%respectively;with and without dietary therapy were 4.31%and 5.66%;with and without oral drug treatment were 4.76%and 3.16%;with and without insulin therapy were 3.49%and 4.66%;With and without complication were 5.81%and 3.83%,respectively.In the "ideal and good control" group the prevalence was 2.69%,while in the "bad control" group the prevalence was 6.43%.No statistic differences were found between any of these groups.Conclusions:Prevalence of dementia is higher in diabetics than in non-diabetics, higher in women than men,and increases as age rises.Prevalence of dementia in diabetics may be higher in long duration of diabetes mellitus and the bad control condition.Part Two Risk factors for dementia in diabeticsObjectives:To study risk factors for dementia in diabetic subjects.Methods:Univariate analysis was used to study risk factors for dementia in diabetic subjects,and multiple logistic regression analysis was used to study independent risk factors for dementia.Odds ratios were generated using univariate analysis results.Results:Univariate analysis suggested that age(P=0.000),gender(P=0.010), education(P=0.025),stroke(P=0.002),atrial fibrillation(P=0.020),economic status (P=0.020),marriage status(P=0.022) and control condition of diabetes mellitus(P=0.066) might be risk factors for dementia in diabetic subjects.Multiple factor logistic regression analysis adjusting for gender,education,atrial fibrillation,economic status and marriage status,revealed that age,stroke and control condition of diabetes mellitus were positively associated with dementia[OR 1.114(1.035-1.198),2.603(1.034-6.553) and 2.901(1.048-8.031),respectively].Conclusions:Age,stroke and control condition of diabetes mellitus are independent risk factors for dementia.