Prevalence and Characteristics of Painful Diabetic Neuropathy in a Large Community-Based Diabetic Population in the UK

Abstract

To assess, in the general diabetic population, 1) the prevalence of painful neuropathic symptoms; 2) the relationship between symptoms and clinical severity of neuropathy; and 3) the role of diabetes type, sex, and ethnicity in painful neuropathy.
Observational study of a large cohort of diabetic patients receiving community-based health care in northwest England (n = 15,692). Painful diabetic neuropathy (PDN) was assessed using neuropathy symptom score (NSS) and neuropathy disability score (NDS).
Prevalence of painful symptoms (NSS ≥5) and PDN (NSS ≥5 and NDS ≥3) was 34 and 21%, respectively. Painful symptoms occurred in 26% of patients without neuropathy (NDS ≤2) and 60% of patients with severe neuropathy (NDS >8). Adjusted risk of painful neuropathic symptoms in type 2 diabetes was double that of type 1 diabetes (odds ratio [OR] = 2.1 [95% CI 1.7-2.4], P < 0.001) and not affected by severity of neuropathy, insulin use, foot deformities, smoking, or alcohol. Women had 50% increased adjusted risk of painful symptoms compared with men (OR = 1.5 [1.4-1.6], P < 0.0001). Despite less neuropathy in South Asians (14%) than Europeans (22%) and African Caribbeans (21%) (P < 0.0001), painful symptoms were greater in South Asians (38 vs. 34 vs. 32%, P < 0.0001). South Asians without neuropathy maintained a 50% increased risk of painful neuropathy symptoms compared with other ethnic groups (P < 0.0001).
One-third of all community-based diabetic patients have painful neuropathy symptoms, regardless of their neuropathic deficit. PDN was more prevalent in patients with type 2 diabetes, women, and people of South Asian origin. This highlights a significant morbidity due to painful neuropathy and identifies key groups who warrant screening for PDN.

Full text

Prevalence and Characteristics of
Painful Diabetic Neuropathy in a Large
Community-Based Diabetic Population
in the U.K.
CAROLINE A. ABBOTT,PHD
1
RAYAZ A. MALIK,PHD
1
ERNEST R.E. VAN ROSS,FRCP
2
JAI KULKARNI,FRCP
2
ANDREW J.M. BOULTON,MD
1
OBJECTIVEdTo assess, in the general diabetic population, 1) the prevalence of painful neu-
ropathic symptoms; 2) the relationship between symptoms and clinical severity of neuropathy;
and 3) the role of diabetes type, sex, and ethnicity in painful neuropathy.
RESEARCH DESIGN AND METHODSdObservational study of a large cohort of di-
abetic patients receiving community-based health care in northwest England (n= 15,692). Pain-
ful diabetic neuropathy (PDN) was assessed using neuropathy symptom score (NSS) and
neuropathy disability score (NDS).
RESULTSdPrevalence of painful symptoms (NSS $5) and PDN (NSS $5 and NDS $3) was
34 and 21%, respectively. Painful symptoms occurred in 26% of patients without neuropathy
(NDS #2) and 60% of patients with severe neuropathy (NDS .8). Adjusted risk of painful
neuropathic symptoms in type 2 diabetes was double that of type 1 diabetes (odds ratio [OR] =
2.1 [95% CI 1.7–2.4], P,0.001) and not affected by severity of neuropathy, insulin use, foot
deformities, smoking, or alcohol. Women had 50% increased adjusted risk of painful symptoms
compared with men (OR = 1.5 [1.4–1.6], P,0.0001). Despite less neuropathy in South Asians
(14%) than Europeans (22%) and African Caribbeans (21%) (P,0.0001), painful symptoms
were greater in South Asians (38 vs. 34 vs. 32%, P,0.0001). South Asians without neuropathy
maintained a 50% increased risk of painful neuropathy symptoms compared with other ethnic
groups (P,0.0001).
CONCLUSIONSdOne-third of all community-based diabetic patients have painful neurop-
athy symptoms, regardless of their neuropathic deficit. PDN was more prevalent in patients with
type 2 diabetes, women, and people of South Asian origin. This highlights a significant morbidity
due to painful neuropathy and identifies key groups who warrant screening for PDN.
Diabetes Care 34:2220–2224, 2011
Neuropathy is one of the most com-
mon long-term complications of di-
abetes and is the main initiating
factor for foot ulceration, Charcot neuro-
arthropathy, and lower-extremity ampu-
tation (1). However, the quality and even
quantity of epidemiological data on
symptomatic diabetic neuropathy remain
poor due to inconsistent definitions, poor
ascertainment, and a lack of population-
based studies. Of three large, clinic-based
studies from Europe, the prevalence of
diabetic polyneuropathy varied from 23
to 29% (2–4). In the Bypass Angioplasty
Revascularization Investigation in Type 2
Diabetes (BARI 2D) cohort of 2,368 type 2
diabetic patients with coronary artery dis-
ease, the prevalence of diabetic peripheral
neuropathy was 51% (5). However, in all of
these studies, although neuropathy symp-
toms were assessed as part of the diagnos-
tic definition of diabetic neuropathy, the
prevalence of painful diabetic neuropathy
(PDN) per se was not established. In our
large, community-based survey of 9,710
predominantly type 2 diabetic patients
derived from general practice in north-
west England, the prevalence of at least
moderate neuropathic deficits as defined
by a neuropathy disability score (NDS
$6) was 22% and at least moderate neu-
ropathy symptoms as defined by the neu-
ropathy symptom score (NSS $5) was
34% (6).
PDN is considered to be the cause of
considerable morbidity and, under the
auspices of the American Academy of
Neurology, evidence-based guidelines
have been published for the manage-
ment of this difficult condition (7). How-
ever, there is a distinct paucity of robust,
population-based epidemiological data on
the prevalence and natural history of this
condition, limited to a few small studies.
Thus, in a small population-based study
of 269 diabetic patients from Wales,
whereas 64% reported pain, only 26%
were confirmed to have PDN, but interest-
ingly those with PDN had a significantly
poorer quality of life compared with those
with nonneuropathic pain (8). In a study of
350 diabetic patients from Liverpool, 13%
of patients with PDN had never reported
their symptoms to their treating physician
and a further 39% had not received any
treatment for PDN (9). In a recent study
of 1,113 diabetic patients attending sec-
ondary care clinics across Turkey, whereas
62% had neuropathy based on abnormal
nerve conduction and clinical examination,
only 16% had neuropathic pain according
to the Leeds Assessment of Neuropathic
Symptoms and Signs score (10).
The natural history of PDN remains
unclear, although in a small longitudinal
study, 77% of 56 diabetic patients with
painful neuropathy were found to con-
tinue with nonabating pain after 5 years
(11). Although it has been suggested that
painful symptoms abate with progressive
worsening of neuropathy, this has not
been supported by a study that has dem-
onstrated equal prevalence of painful
symptoms in those with mild compared
with more advanced neuropathy (12).
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From the
1
Division of Cardiovascular Medicine, Core Technology Facility, University of Manchester,
Manchester, U.K.; and the
2
Disablement Services Centre, Withington Hospital, Manchester, U.K.
Corresponding author: Caroline A. Abbott, caroline.abbott@manchester.ac.uk.
Received 13 June 2011 and accepted 5 July 2011.
DOI: 10.2337/dc11-1108
Ó2011 by the American Diabetes Association. Readers may use this article as long as the work is properly
cited, the use is educa tional and not for profit, and the work is not alte red. See http://creativecommons.org/
licenses/by-nc-nd/3.0/ for details.
2220 DIABETES CARE,VOLUME 34, OCTOBER 2011 care.diabetesjournals.org
Epidemiology/Health Services Research
ORIGINAL ARTICLE

Therefore there is a significant lack of
large, population-based data defining the
size of the neuropathic pain problem and
attempting to provide some explanations
toward pain etiology. We have had the
unique opportunity to assess the follow-
ing in a large, community-based diabetic
population: 1) the prevalence of painful
neuropathic symptoms; 2)therelation-
ship between neuropathic symptoms
and severity of clinical neuropathy; 3)the
differences in neuropathic symptoms be-
tween patients with type 1 and type 2 di-
abetes; and 4) the role of sex and ethnicity.
RESEARCH DESIGN AND
METHODSdThe North-West Diabetes
Foot Care Study (NWDFCS), a population-
based investigation of diabetes-related
foot problems in the community health
care setting, provided the study popula-
tion (6). The study was approved by the
local research ethics committees, general
practitioner (GP)–based diabetes teams,
and hospital-based diabetes teams in
each district and was funded by the De-
partment of Health. One full-time re-
search podiatrist or research nurse was
appointed to screen diabetic patients in
the GP practices, diabetes centers, and
hospital outpatient clinics for each district.
At GP practices, the vast majority of pa-
tients were screened while attending for
their annual review; others were screened
while attending podiatry clinics. Remain-
ing patients were invited to attend a spe-
cial clinic at the practice, or the patient was
visited residentially. Each patient was as-
sessed once for symptoms and signs of
peripheral neuropathy, peripheral vascular
disease (less than or equal to two palpable
pedal pulses), demographic data, and med-
ical history during a short (20–30 min)
screening session.
Assessment of neuropathy
Peripheral neuropathy was assessed as pre-
viously described (6). Neuropathic deficits
in the feet were determinedusing the NDS,
derived from inability to detect pin-prick
sensation (using Neurotip), vibration (us-
ing 128-Hz tuning fork), and differences in
temperature sensation (using warm and
cool rods) plus Achilles reflex (using ten-
don hammer) (6).
NSS
Patients were asked about their experi-
ence of pain or discomfort in the legs. If
the patient described burning, numbness,
or tingling, a score of 2 was assigned;
fatigue, cramping, or aching scored 1.
The presence of symptoms in the feet was
assigned a score of 2, the calves 1, and
elsewhere a score of 0. Nocturnal exacer-
bation of symptoms scored 2 vs. 1 for both
day and night and 0 for daytime alone. A
score of 1 was added if the symptoms had
ever woken the patient from sleep. The
patients were asked if any maneuver could
reduce the symptoms; walking was as-
signed a score of 2, standing 1, and sitting
or lying down 0. The maximum symptom
score was 9. The severity of symptoms was
graded according to the NSS as follows:
none (0–2), mild (3–4), moderate (5–6),
and severe (7–9) (2). The NSS has been
used as part of the assessment of PDN in
several previous studies (2,9,11,13). We
defined PDN as at least moderate symp-
toms with mild neurologic signs (NSS
score $5 and NDS score $3) (9,11).
Statistical analysis
Variables were stratified into normal and
abnormal categories, and x
2
tests were
performed for categorical data. Normally
distributed, continuous data were tested
using Student ttest, whereas nonnor-
mally distributed data were first analyzed
using Kruskal-Wallis, followed by a Mann-
Whitney Utest. After obtaining 95% CIs,
age-adjusted prevalence rate differences
were evaluated between the diabetes
type, sex, and ethnic groups. Logistic re-
gression was used to obtain odds ratios
(ORs) for neuropathy symptoms between
the comparison groups. Modifiers of the
ORs were entered into the final logistic re-
gression models to determine which risk
factors may account for symptom differ-
ences. Statistical package SPSS 16.0 was
used to analyze data.
RESULTSdOver 4 years, our community-
based screening program assessed 15,692
patients with diabetes within six health care
districts of northwest England, represent-
ing w60% of involved GPs’diabetic pa-
tients (6,14). The majority (70%) of
patients were screened while attending
their diabetes annual review in primary
care, with the remainder (30%) screened
at referral sites in diabetes centers and hos-
pital outpatient clinics.
Demographic and medical character-
istics of the entire community-based di-
abetic cohort and type 1 and 2 diabetic
subcohorts are given in Table 1. The pa-
tients with type 2 diabetes were substan-
tially older than those with type 1 diabetes
(63.6 611.8 vs. 37.6 612.9 years, re-
spectively) and had a greater proportion
of South Asian/African Caribbean patients
(15.1 vs. 3.9%, respectively). Duration of
type 2 diabetes was one-quarter that of
thetype1group(P,0.0001). Type 2
diabetic patients were less likely to be cur-
rent smokers (22 vs. 33%, P,0.0001).
Despite substantially greater levels of clin-
ical neuropathy, peripheral arterial dis-
ease (PAD), and foot deformities in the
type 2 diabetic patients, foot ulcer rates
(past or present) were similar between
the two groups (4.9 vs. 6.0%, respectively,
P= 0.07). Paradoxically, lower-limb am-
putation rate was significantly lower in
type 2 compared with type 1 diabetic pa-
tients (1.2 vs. 1.8%, P,0.05).
Prevalence of painful neuropathy
The distribution of neuropathy symptom
severity within the entire cohort was as
follows: no symptoms (NSS 0–2) = 52%
(8,073/15,638), mild symptoms (NSS 3–4) =
14% (2,254/15,638), moderate symptoms
(NSS 5–6) = 18% (2,780/15,638), and se-
vere symptoms (NSS 7–9) = 16% (2,531/
15,638). The overall prevalence of painful
neuropathy symptoms (i.e., NSS $5) in
this cohort was 34% (5,311/15,638).
Relationship between neuropathy
symptoms and clinical severity of
neuropathy
The prevalence of painful neuropathy
symptoms in the presence of clinical
neuropathy (PDN) (i.e., NSS score $5
and NDS score $3) for all patients was
21% (3,242/15,614). The distribution of
increasing neuropathy symptoms in pa-
tient groups stratified by the severity of
clinical neuropathy is given in Fig. 1.
Sixty percent (379/629) of diabetic pa-
tients with severe clinical neuropathy
(NDS .8) had painful neuropathic symp-
toms (NSS $5), whereas only 26%
(2,060/8,016) of patients without clinical
neuropathy (NDS #2) had painful symp-
toms. There was an emerging pattern of
worsening clinical neuropathy scores as-
sociated with an increasing proportion of
patients with more severe painful neuro-
pathic symptoms (P,0.0001), and there
was a significant, positive correlation
between NSS and NDS (r= 0.24, P,
0.0001). This relationship between signs
and symptoms was stronger in type 1 (r=
0.37, P,0.0001) than type 2 diabetic
subjects (r= 0.22, P,0.0001).
Type 1 versus type 2 diabetes
Painful symptoms (NSS $5) were more
prevalent in type 2 (35.0% [4,962/14,166])
versus type 1 (22.7% [303/1,334], P,
0.0001) diabetic patients, as was PDN
care.diabetesjournals.org DIABETE S CARE,VOLUME 34, OCTOBER 2011 2221
Abbott and Associates

(21.5% [3,039/14,144] vs. 13.4% [178/
1,333], respectively, P,0.0001). The
risk of painful neuropathy symptoms in
type 2 diabetic patients was 83% higher
than in type 1 patients (OR = 1.8 [95%
CI 1.6–2.1], P,0.0001); this risk dou-
bled after adjusting for differences in age
and diabetes duration (OR = 2.1 [1.7–
2.4], P,0.0001). When examining pa-
tients with moderate to severe clinical
neuropathy (i.e., NDS $6) only, the age-
and diabetes duration–adjusted risk of
painful symptoms in type 2 versus type 1
diabetic patients was still significantly
greater (OR = 1.8 [1.2–2.5], P,0.0001).
Adjustment for type 2 versus type 1 di-
abetes and differences in severity of neu-
ropathy, insulin use, foot deformities,
smoking status, and alcohol intake had
no impact on these differences in painful
symptoms (data not shown); i.e., these
variables could not account for the dis-
parity in symptoms between type 1 and
type 2 diabetes.
Age effect
Increasing age was very weakly associated
with NSS severity in the entire population
(r=0.083,P,0.0001); however, this
relationship was stronger in type 1
(r=0.20,P,0.0001) than type 2 diabetes
(r= 0.022, P= 0.008). Indeed, increasing
age categories in type 1 diabetic patients
showed an almost doubling in prevalence
of painful symptoms (NSS $5) (aged
,35 years, 17.2%; 35–54 years, 26.4%;
55+ years, 33.1%; P,0.0001), with a
similar, but less marked, association in
type 2 diabetic patients (aged ,35 years,
30.6%; 35–54 years, 32.7%; 55+ years,
35.7%; P,0.01).
Effect of diabetes treatment
Insulin use versus oral hypoglycemic
agents (OHAs) and/or diet had no effect
on painful neuropathy symptoms, i.e.,
33% (1,085/3,272) of patients using in-
sulin had NSS $5comparedwith34%
Table 1dDemographic and medical characteristics of patient cohorts
Characteristic Total population Type 1 diabetes Type 2 diabetes P
N15,692 1,338/15,544 (8.6%) 14,206/15,544 (91.4%) d
Male 8,448/15,684 (53.9%) 750/1,338 (56.1%) 7,631/14,203 (53.3%) 0.10
Age (years) 61.4 614.0 37.6 612.9 63.6 611.8 ,0.0001
Duration of diabetes (years) 5 (2–10) 17 (10–26) 4 (2–10) ,0.0001
Ethnicity
White European 13,409/15,692 (85.5%) 1,283/1,338 (96.0%) 12,015/14,206 (84.6%)
South Asian 1,866/15,692 (11.9%) 42/1,338 (3.1%) 1,791/14,206 (12.6%)
African Caribbean 371/15,692 (2.4%) 11/1,338 (0.8%) 357/14,206 (2.5%)
Other 46/15,692 (0.2%) 2/1,338 (0.1%) 43/14,206 (0.3%) ,0.0001
Diabetes treatment
Diet only 4,643/15,622 (29.7%) d4,601/14,163 (32.5%)
OHA + diet 7,696/15,622 (49.3%) d7,637/14,163 (53.9%)
Insulin (6OHA) 3,283/15,622 (21.0%) 1,337/1,337 (100.0%) 1,925/14,163 (13.6%) ,0.0001
Overt nephropathy 440/15,274 (2.9%) 58/1,308 (4.4%) 379/13,841 (2.7%) ,0.001
Impaired vision 1,700/15,455 (11.0%) 108/1,319 (8.2%) 1,574/14,006 (11.2%) ,0.001
Smoking history
Never smoked 6,568/15,632 (42.0%) 626/1,335 (46.8%) 5,859/14,156 (41.4%)
Current smoker 3,581/15,632 (22.9%) 445/1,335 (33.3%) 3,111/14,156 (22.0%)
Ex-smoker 5,483/15,632 (35.1%) 264/1,335 (19.7%) 5,186/14,156 (36.6%) ,0.0001
Alcohol ($7 units/week) 6,998/15,474 (45.2%) 877/1,323 (66.3%) 6,074/14,020 (43.3%) ,0.0001
Clinical neuropathy 3,333/15,659 (21.3%) 217/1,337 (16.2%) 3,077/14,183 (21.7%) ,0.0001
Foot deformities 4,699/15,600 (30.1%) 204/1,335 (15.3%) 4,444/14,126 (31.5%) ,0.0001
Peripheral arterial disease 3,139/15,664 (20.0%) 139/1,337 (10.4%) 2,957/14,186 (20.8%) ,0.0001
Foot ulcer history 774/15,484 (5.0%) 80/1,331 (6.0%) 684/14,015 (4.9%) 0.070
Lower-limb amputation history 191/15,422 (1.2%) 24/1,327 (1.8%) 164/13,955 (1.2%) 0.045
Data are mean 6SD, n(%), or median (25th–75th percentiles); Pvalues for type 1 vs. type 2.
Figure 1dPercentage prevalence of neuropathic symptoms in 15,659 diabetic patients char-
acterized by their level of clinical neuropathy.
2222 DIABETES CARE,VOLUME 34, OCTOBER 2011 care.diabetesjournals.org
Painful diabetic neuropathy in the community

(4,206/12,303) of patients treated with
diet and OHA (P= 0.27). However, when
treatments were examined individually,
symptoms were most prevalent in patients
treated with OHA (37.3%) compared with
insulin (33.2%) or diet alone (29.1%)
(P,0.0001). Restricting the analysis to
patients with clinical neuropathy, painful
symptoms were most prevalent in the
insulin-treated group .OHA group .
diet-only group (54.7, 50.6, and 42.1%,
respectively; P,0.0001).
Effect of sex
Asignificantly greater proportion of
females (38% [2,732/7,212]) than males
(31% [2,578/8,423]) reported painful
neuropathy symptoms (P,0.0001), de-
spite fewer females than males having
clinical neuropathy (NDS $6) (19 vs.
23%, P,0.0001). PDN (NSS $5and
NDS $3) was, similarly, more prevalent
in females than males (23 vs. 19%, respec-
tively, P,0.0001). After adjustments for
age, diabetes duration, and differences in
clinical neuropathy, women still had a
50% increased risk of painful symptoms
compared with men (OR = 1.5 [95% CI
1.4–1.6], P,0.0001).
Effect of ethnicity
Despite a lower unadjusted prevalence of
clinical neuropathy (NDS $6) in South
Asians (14%) compared with Europeans
(22%) and African Caribbeans (21%)
(P,0.0001), painful neuropathy symp-
toms (NSS $5) were significantly and,
conversely, greater in South Asians (38%)
compared with Europeans (34%) and
African Caribbeans (32%) (P,0.0001).
Greater neuropathy symptoms in South
Asians, however, were only evident in pa-
tients without clinical neuropathy (i.e.,
NSS $5 and NDS #2: South Asians 19%
[352/1,845], Europeans 13% [1667/
13,354], African Caribbeans 10% [36/
370]; P,0.0001), whereas PDN (NSS
$5andNDS$3) was similarly prevalent
in all ethnic groups (21% [2,803/13,354],
19% [349/1,845], and 22% [80/370], re-
spectively; P= 0.11). After adjustments for
age and diabetes duration, South Asians
without significant clinical neuropathy
were still 50% more likely to have painful
neuropathy symptoms compared with
other ethnic groups (OR = 1.5 [95% CI
1.3–1.6], P,0.0001).
CONCLUSIONSdWe have shown
that one-third of all patients with diabetes
in the community have painful neuropathic
symptomatology, regardless of whether
they have clinical neuropathy. These data
show a higher prevalence of painful neuro-
pathic symptoms than previously reported
in two small population-based studies
(9,11). In a recent study using the vali-
dated DN4 (a clinician-administered neu-
ropathic pain diagnostic questionnaire),
the prevalence of PDN in 1,039 diabetic
patients in secondary care was found to be
65% (15). Our current data indicate a
large morbidity for neuropathic pain in a
community-based diabetic population.
They also challenge the dogma that pain-
ful neuropathic symptoms improve as the
severity of neuropathy worsens and pro-
vide support for a previous study that
actually demonstrated comparable preva-
lence of painful neuropathy in diabetic
patients with mild and more severe neu-
ropathy (12). Furthermore, approximately
one-quarter of our patients without clini-
cal neuropathy on examination had signif-
icant painful neuropathic symptoms,
indicating the large disparity between
signs and symptoms. But of course even
patients with impaired glucose tolerance
and no apparent neuropathy develop
painful neuropathic symptoms and small
nerve fiber damage (16). This emphasizes
the need to ask all patients about the oc-
currence of painful neuropathic symp-
toms, not just those who have clinical
neuropathy. Painful symptoms were twice
as prevalent in type 2 versus type 1 dia-
betic patients, even after adjusting for dif-
ferences in age, neuropathy, PAD, and
other known risk factors for neuropathic
pain (17). These data are consistent with a
previous study that demonstrated a higher
prevalence of clinical neuropathy in type 2
compared with type 1 diabetic patients,
assessed using a combination of the NSS
and NDS (2). Previously, the prevalence of
PDN has not been found to differ between
type 1 and type 2 diabetes, although the
proportion of patients with type 1 diabe-
tes was very small (9,15). Women had a
50% increased risk of painful symptoms
compared with men. This has also been
demonstrated recently in a study from
Saudi Arabia (15). This latter study dem-
onstrated no ethnic differences for the
incidence of PDN (15). In the current
study, however, we demonstrate a sig-
nificantly higher prevalence of painful
neuropathic symptoms in South Asians
compared with Europeans and African
Caribbeans, with a 50% increased risk
of neuropathic pain in South Asians in
the absence of clinical neuropathy. Para-
doxically, we have previously demon-
strated a lower prevalence of both large
and small fiber neuropathy (18), as well
as incidence of foot ulceration (14), in
South Asians.
The major strength of this epidemio-
logical study, compared with others, is
that it is substantially larger than any
previously published study on the prev-
alence of PDN. Furthermore, it is com-
munity based and therefore reflects the
magnitude of this problem in a nonse-
lected cohort of diabetic patients. As this
study was designed to be totally inclusive
for community-based patients with dia-
betes, we did not exclude patients with
neuropathic pain from an etiology other
than diabetes, or attempt to identify pain
from a different origin. We did not assess
the duration of pain, hence the prevalence
of chronic pain ($6months)couldnot
be established. The use of medications
for the treatment of neuropathic pain
was not recorded. We used the NSS as
it is relatively quick to administer and is
weighted toward positive neuropathic
symptoms in the lower limbs, consistent
with PDN. Indeed, three key lower-limb
symptoms that characterize neuropathic
from nonneuropathic pain are tingling
pain, numbness, and increased pain due
to touch (19) and are incorporated in the
NSS. Numbness or “cotton wool-like feel-
ing”is a positive, identifiable, painful symp-
tom described by patients and thus different
to loss of sensation, which patients may or
may not be aware of. These symptoms were
captured by the NSS along with a measure
of the distribution, presence of nocturnal
exacerbation, and relieving factors.
The demonstration that one-third of all
diabetic patients have significant tingling/
shooting, burning pain, with or without
numbness, in the lower limbs indicates
a larger morbidity than previously estab-
lished in relatively small and selective
studies in the U.K. (9,11) and in a recent
larger, but selected, population-based
study from Germany (17). Our finding
that one-quarter of community patients
without clinical neuropathy have painful
neuropathic symptoms implies that a large
proportion of the diabetic community are
being neglected in the treatment of their
symptoms, and that classic neuropathic,
lower-limb symptoms may well be inap-
propriately considered “nonneuropathic”
if there are no concomitant signs of clinical
neuropathy. Davies et al. (8) also showed
that a significant proportion (7.4%) of
subjects with PDN using the Toronto
Clinical Scoring System had no clinical
signs of neuropathy. We have extended
this observation in a large cohort of
care.diabetesjournals.org DIABETE S CARE,VOLUME 34, OCTOBER 2011 2223
Abbott and Associates

patients and shown that w40% of all pa-
tients without signs of neuropathy will
have at least mild neuropathic symptoms.
To conclude, we have observed greater
neuropathic pain levels in type 2 diabetes,
in women, and in people of South Asian
origin. These areas demand further inves-
tigation and also highlight key groups who
may warrant screening for PDN.
AcknowledgmentsdFunding of the NWDFCS
foot screening program was originally provided
by the Department of Health.
No potential conflicts of interest relevant to
this article were reported.
C.A.A. coordinated the study, monitored
data collection, c leaned and analyzed data, and
drafted and revised the manuscript. R.A.M.
analyzed data and drafted and revised the
manuscript. E.R.E.v.R. and J.K. designed the
project and revised the manuscript. A.J.M.B.
initiated and designed the project and drafted
and revised the manuscript.
Parts of this study were presented orally at
the 71st Scientific Sessions of the American
Diabetes Association, San Diego, California,
24–28 June 2011.
The authors would like to thank all original
members of the NWDFCS who implemented
the foot screening and data collection.
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Painful diabetic neuropathy in the community