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doi: 10.1093/ageing/afp166
Published electronically 11 September 2009
© The Author 2009. Published by Oxford University Press on behalf of
the British Geriatrics Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution NonCommercial License (http://creativecommons.org/licenses/by-nc/2.5),
which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Risk factors of new onset diabetes mellitus
among elderly Chinese in rural Taiwan
SIR—Diabetes mellitus (DM) is associated with a strong
negative impact on the health care system, directly causing
5.2% of all deaths in the world [1]. Certain risk factors for
developing DM have been identified, including older age [2].
Among all ethnic groups studied so far, the prevalence of
DM may reach 20% in older people [3–5], and older diabetic
patients are more likely to develop diabetic microangiopathy,
atherosclerotic vascular diseases [5] and to die from DM [6, 7].
They are also more likely to develop cardiovascular diseases
than younger diabetic patients or non-diabetic elderly people
[5, 8]. Moreover, older diabetic patients are more prone to
have physical disabilities, cognitive impairment and depression [9]. Accurate diagnosis and appropriate intervention
programmes for older diabetic patients may successfully prevent DM-related complications [10–12]. However, evidence
supporting current diagnostic criteria, prevention strategies
and targets for glycaemic control in the older population
are not fully developed [13, 14]. Tight glycaemic control
may successfully reduce the risk of microvascular and
macrovascular complications in adults [15], but we lack evidence that these effects are relevant in the older population.
For example, older men with late onset DM had similar mortality to non-diabetic subjects in long-term follow-up [16].
Thus, strategies regarding diagnosis, screening and treatment
in later onset DM remain controversial.
The main purpose of this study was to evaluate risk factors for the development of DM in older rural Taiwanese
residents.
Methods
In 2000, people aged over 40 living in three major townships
of I-Lan County, who participated in the annual physical examinations, were invited for study. The study protocol has
been reported before [4, 17]. Subjects aged 65 years were
selected from the primary cohort and followed up in
2005. In 2000, research staff performed a thorough physical
examination, and fasting samples were taken to estimate
fasting plasma glucose (FPG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C),
creatinine and FI.
Obesity was defined as the body mass index (BMI) over
25 kg/m2, and overweight was defined when 23 < BMI <
25 kg/m2 [18]. Insulin resistance was determined by homeostasis model assessment (HOMA-IR) [19], and the insulin
resistant state was defined as the highest quartile of
HOMA-IR among the lean subjects (BMI <25 kg/m2 )
[20]. The estimated glomerular filtration rate (eGFR) was
calculated by the Modification of Diet in Renal Disease
study, and chronic kidney disease (CKD) was defined when
eGFR <60 ml/min/1.73 m2 [21]. Overt proteinuria was determined by dipstick urine analysis. Metabolic syndrome
(MS) was defined according to the Adult Treatment Panel
III standard, and the cutoffs of waist circumferences were
modified, according to Asian-Pacific recommendations, to
90 cm in males and 80 cm in females.
With assistance from local health stations and county
government, research staff followed up the subjects in
2005. All subjects in the primary cohort were surveyed by
telephone contact and a detailed health record review or personal visits. DM status was determined by the medical
records (both medication use and laboratory testing), self report or plasma glucose testing. New onset diabetes (NOD)
125
Research letters
Table 1. Demographic data of all study subjects in three
major townships of I-Lan County in 2000
Item (n = 585)
Frequency or mean ± SD
............................................................
Age (years)
Sex (male, %)
Hypertension (%)
Diabetes mellitus (%)
MS (%)
Mean BMI (kg/m2)
Obesity (%)
Overweight (%)
Serum TC (mmol/L)
Serum TG (mmol/L)
Serum HDL-C (mmol/L)
Serum LDL-C (mmol/L)
HOMA-IR
Insulin resistance (%)
GFR (ml/min/1.73 m2)
CKD (%)
Overt proteinuria (%)
72.6 ± 6.0
49.2
47.5
16.9
37.2
24.1 ± 3.8
37.2
23.5, 23.4
5.38 ± 1.02
1.43 ± 0.91
1.20 ± 0.46
3.53 ± 0.94
1.9 ± 3.1
36.7
62.4 ± 13.7
47.7
16.6
TC, total cholesterol; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; LDL-C, low density lipoprotein cholesterol.
hort. The prevalence of DM was 16.9% in 2000, and
impaired fasting glucose (IFG) was 25.5%. In 2005, 48
(8.2%) people had died, and 171 subjects had moved out
of the geographic area or refused to be followed up, so they
were excluded. Overall, 358 subjects (mean age = 76.5 ± 5.1
years, 47.7% males) completed the study (Table 1). During
the study period, the prevalence of DM increased from 16.9
to 23.7% and IFG from 25.5 to 27.9%.
Overall, the 5-year cumulative incidence of NOD was
6.8%. Thirty-two subjects developed NOD, and six subjects
became non-diabetic. Table 2 showed comparisons between
subjects with NOD and the remaining non-diabetic during
the study period (subjects who remained diabetic both in
2000 and 2005 were excluded from the comparisons).
NOD subjects were significantly more likely to be hypertensive, overweight or obese, to have IFG, insulin resistance
and overt proteinuria. Meanwhile, the NOD subjects had
a higher mean BMI, FPG, serum TC and HOMA-IR in
2000 (Table 2).
Multiple logistic regression analysis showed that hypertension (OR, 3.47; 95% CI, 1.19–10.17; P = 0.023), overt
Table 2. Comparisons of demographic data and laboratory results in 2000 between subjects with and without new onset DM
Item
Non-diabetic (n = 271)
New onset DM (n = 32)
P value
70.9 ± 5.4
48.0%
43.2%
27.5%
23.8 ± 3.7
55.4%
5.23
26.6%
5.39 ± 0.87
1.37 ± 0.97
1.25 ± 0.48
3.51 ± 0.88
1.1 ± 1.2
25.4%
63.5 ± 12.5
45.4%
9.6%
71.7 ± 5.1
40.6%
65.6%
40.0%
26.1 ± 3.7
81.3%
5.72
59.4%
5.92 ± 1.40
1.67 ± 0.87
1.30 ± 0.44
3.87 ± 1.34
1.9 ± 1.8
59.1%
63.6 ± 10.9
50.0%
31.3%
0.448
0.460
0.023*
0.245
0.002*
0.002*
0.001*
<0.001*
0.002*
0.082
0.633
0.067
0.010*
0.002*
0.984
0.709
0.002*
.............................................................................................................................
Age (years)
Sex (male, %)
Hypertension (%)
MS (%)
BMI (kg/m2)
Overweight or obesity (%)
FPG (mmol/L)
IFG (%)
Serum TC (mmol/L)
Serum TG (mmol/L)
Serum HDL-C (mmol/L)
Serum LDL-C (mmol/L)
HOMA-IR
Insulin resistance (%)
GFR (ml/min/1.73 m2)
CKD (%)
Overt proteinuria (%)
*P < 0.05.
mellitus was defined as subjects who were non-diabetic in
2000 and became diabetic in 2005.
Data presented in the text and tables are expressed as
mean ± standard deviation. Comparisons between groups
were done by Chi-square test or Student t test (SPSS 13.0,
Chicago, IL, USA) as appropriate. Multiple logistic regression was used to determine risk factors for NOD. For all
tests, a P value <0.05 (two-tailed) was considered statistically
significant.
Results
In total, 585 subjects aged over 65 years (mean age = 72.6 ±
6.0 years, 49.2% males) were identified in the primary co-
126
proteinuria (OR, 3.41; 95% CI, 1.07–10.92; P = 0.039),
IFG (OR, 3.07; 95% CI, 1.11–8.52; P = 0.031) and higher
serum TC (OR, 1.02; 95% CI, 1.01–1.03; P = 0.006) were
independent risk factors for NOD.
Discussion
In an older Taiwanese population, we have shown that the 5year incidence of NOD is 6.8% with hypertension, proteinuria and a raised TC level all acting as independent risk
factors for NOD. The crude prevalence of DM in this study
was lower than previous reports in other parts of the world
(33.4% in Hispanic, 29.6% in black and 18.4% in white people) [22] and similar to estimates from other Chinese
Research letters
populations [23, 24]. Differences may relate to ethnicity and
lifestyle, with the majority of our study subjects having been
farmers for decades.
We found similar rates of risk factors for DM to those seen
in previous studies, including rates of IFG, insulin resistance,
hypertension, dyslipidemia, poorer renal function, higher serum levels of uric acid and higher BMI [25]. However, neither
insulin resistance nor overweight/obesity was a risk factor for
NOD in our study. Previous studies have shown that proteinuria predicts NOD; but the precise pathophysiology remains
unclear [26]. In this study, proteinuria preceded DM incidence
in many cases, possibly reflecting a clustering of multiple cardio-metabolic risk factors in affected subjects.
Hypercholesterolemia predicting NOD is a new finding
in this study. Serum TC declines with age [27]. However,
simultaneous elevation of fasting glucose and cholesterol
has been observed among older people with impaired glucose metabolism [28]. Overweight/obesity was not an
independent risk factor for NOD in this study. Although it
may be hypothesised that weight reduction and increased adiposity with age may promote DM development, a study in
Japan showed that overweight or obesity was less important
in DM development in older people than the middle-aged
population [29].
We acknowledge some limitations in this study. Subjects
were volunteers participating in annual health examinations
and from a predominantly rural background. The frailest elderly people were not recruited. However, the role of DM
screening and treatment in frail older people is yet to be determined. Also, FPG was used as a screening test (in
accordance with ADA guidelines at that time [30]), but an
oral glucose tolerance test may have identified older people
with postprandial hyperglycaemia but not fasting hyperglycaemia. Finally, the prevalence of DM and IFG reached
42.2% in the primary cohort, which may bias the incidence
of NOD, with older people over-represented and therefore
promoting a high prevalence of DM and IFG in this study.
A prospective cohort study focused on older people with
normal glucose tolerance may provide more in-depth information to evaluate the risk factors of NOD among older
people. Such a study can be informed by this one, with an
anticipated annual incidence of diabetes of 1.4%, and hypertension, proteinuria, fasting glucose and serum cholesterol
are all important parameters for measurement.
Key points
• Cardiovascular risk factor clustering is present in older
people with NOD.
• The 5-year cumulative incidence of NOD among older
Taiwanese was 6.8%.
• Older people in rural Taiwan with hypertension, overt
proteinuria, IFG and higher serum TC were more prone
to develop NOD in a 5-year follow-up.
Conflicts of interest
The authors have no conflicts of interest.
LI-NING PENG1,4, MING-HSIEN LIN1,4, HSIU-YUN LAI1,4,
SHINN-JANG HWANG2,4, LIANG-KUNG CHEN1,4, *, SHU-TI CHIOU3
1
Division of Geriatric Medicine, Department of Family Medicine,
Taipei Veterans General Hospital, Taipei, Taiwan
2
Department of Family Medicine,
National Yang Ming University School of Medicine, Taipei, Taiwan
3
Department of Public Health and Social Medicine,
National Yang Ming University School of Medicine, Taipei, Taiwan
4
Department of Family Medicine,
Taipei Veterans General Hospital, No 201,
Shih-Pai Road Sec 2, Taipei 11217, Taiwan
E-mail: [email protected]
*To whom correspondence should be addressed
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128
The underdetection of cognitive impairment
in nursing homes in the Dublin area. The
need for on-going cognitive assessment
SIR—Cognitive impairment (CI) or dementia may now be a
major concern of Irish nursing homes (NHs) [1]. In the
USA and Europe, between one-half and two-thirds of NH
residents are said to have dementia [2–8]. Whilst one should
exercise caution in comparing NH populations in different
countries, due to large differences existing between facilities,
in general private [9], smaller [3] and urban facilities [3] have
been shown to have a higher prevalence of residents with
dementia.
Diagnosis has been called ‘the gateway for care’ [11]. Differential diagnosis is also the gateway to appropriate medical
and drug treatment. Dementia with Lewy body (DLB) for
example must be excluded before commencing anti-psychotic (AP) drugs. In residential care, diagnosis and staffs'
assessment of residents' cognitive status is essential for optimal treatments [4, 10]. The absence of knowledge about
residents' memory and cognitive status may also seriously
compromise care services and quality of life. Mild and moderate dementia are more frequently overlooked than severe
[12]. Low expectations of cognitive functioning and the absence of challenging behaviours often hinder staffs'
recognition of dementia [4, 10]. One UK study showed that
only 34% of residents classified on Mini-Mental State Examination (MMSE) as cognitively impaired were acknowledged
by senior nursing staff as having dementia [10]. For those
with a severe impairment, a higher number (46.4%) were recognised [10]. In a Danish study, key carer staff [4] correctly
identified some 74% of the residents that had a dementia or
other brain disorder.
Recent Irish research, based on the 2002 Census, estimated that there were some 14,764 people aged 65 and
over living in NHs of whom 85% experienced a disability
[13]. Of these, large numbers may have had CI or dementia
since 58% had difficulties ‘learning, remembering and concentrating’. Regrettably in the Census, no direct question
was asked about dementia or CI nor has any recent audit
of Irish NHs been undertaken for dementia or CI since.
This study was undertaken to address this gap in our understanding and to test a methodology for a future larger
national survey of CI across NHs in Ireland.
Methods
Sampling of NHs
All general private and voluntary NHs belonging to the former Irish Health Service Executive East Coast Area (Dublin
Mid-Leinster) were sampled. Three areas, namely 1, (Dun
Laoire), 2 (Dublin South East) and 10 (Wicklow) which represent the former East Coast Eastern Regional Health
Authority provided the sampling frame. Four of the 53
NHs were randomly selected. The chance of a NH being
sampled was directly proportional to its size.