Oral sildenafil in the treatment of erectile dysfunction in diabetic men: a randomized double-blind and placebo-controlled study.

Abstract

To determine the efficacy and safety of oral sildenafil citrate in the treatment of erectile dysfunction (ED) in diabetic men.
In a randomized, double-blind, placebo-controlled, and fixed-dose study, a total of 282 men (mean age, 46.4 years) with ED (mean duration, 3.6 years) and diabetes (mean duration, 11 years) were randomly assigned to receive 100 mg sildenafil (n=144) or placebo (n=138) approximately 1 h before planned sexual activity, but not more than once daily, for 16 weeks. The efficacy of two treatments was assessed using responses to the International Index of Erectile Function (IIEF) questionnaire.
Two hundred sixty-two (93%) of men completed the study (134/144 in the sildenafil group, 128/138 in the placebo group). Positive clinical results were obtained in 68 (51%) of 134 patients in the sildenafil group compared with 14 (11%) of 128 patients in the placebo group (P<.003). Fifty-nine percent of the patients reported at least one successful attempt at sexual intercourse in the sildenafil group as compared with 21% successful attempts for the placebo group (P<.002). Drug-related adverse effects occurred in 32 (22%) of 144 patients taking sildenafil and 4 (3%) of 138 patients receiving placebo. The most common adverse events were headache (20% sildenafil, 2% placebo), flushing (19% sildenafil, 0% placebo), dyspnea (9% sildenafil, 2% placebo), rhinitis (6% sildenafil, 0% placebo), and cardiovascular effects (7% sildenafil, 0% placebo). Of patients taking sildenafil, four (2.7%) developed new chest pains, with documented myocardial infarction in two.
Oral sildenafil is a moderately effective treatment for ED in men with diabetes. The response rate was lower and cardiovascular events were higher than previously reported in nondiabetic patients.

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Oral sildenafil in the treatment of erectile dysfunction in diabetic men
A randomized double-blind and placebo-controlled study
Mohammad R. Safarinejad*
Department of Urology, Military University of Medical Sciences, P.O. Box 19395-1849, Tehran, Iran
Received 14 February 2003; received in revised form 6 April 2003; accepted 15 April 2003
Abstract
Purpose: To determine the efficacy and safety of oral sildenafil citrate in the treatment of erectile dysfunction (ED) in diabetic men.
Materials and methods: In a randomized, double-blind, placebo-controlled, and fixed-dose study, a total of 282 men (mean age, 46.4 years)
with ED (mean duration, 3.6 years) and diabetes (mean duration, 11 years) were randomly assigned to receive 100 mg sildenafil (n=144) or
placebo (n=138) approximately 1 h before planned sexual activity, but not more than once daily, for 16 weeks. The efficacy of two
treatments was assessed using responses to the International Index of Erectile Function (IIEF) questionnaire. Results: Two hundred sixty-two
(93%) of men completed the study (134/144 in the sildenafil group, 128/138 in the placebo group). Positive clinical results were obtained in
68 (51%) of 134 patients in the sildenafil group compared with 14 (11%) of 128 patients in the placebo group (P<.003). Fifty-nine percent
of the patients reported at least one successful attempt at sexual intercourse in the sildenafil group as compared with 21% successful attempts
for the placebo group (P<.002). Drug-related adverse effects occurred in 32 (22%) of 144 patients taking sildenafil and 4 (3%) of 138
patients receiving placebo. The most common adverse events were headache (20% sildenafil, 2% placebo), flushing (19% sildenafil, 0%
placebo), dyspnea (9% sildenafil, 2% placebo), rhinitis (6% sildenafil, 0% placebo), and cardiovascular effects (7% sildenafil, 0% placebo).
Of patients taking sildenafil, four (2.7%) developed new chest pains, with documented myocardial infarction in two. Conclusion: Oral
sildenafil is a moderately effective treatment for ED in men with diabetes. The response rate was lower and cardiovascular events were higher
than previously reported in nondiabetic patients.
D 2004 Elsevier Inc. All rights reserved.
Keywords: Sildenafil; Penile erection; Erectile dysfunction; Diabetes
1. Introduction
Erectile dysfunction (ED) is a common complication of
diabetes and an important cause of decreased quality of life
in men with diabetes (NIH Consensus Conference, 1993).
The prevalence of ED of any degree in men aged 40 to 70
years was estimated to be 52% in the Massachusetts Male
Aging Study, with a prevalence of 25% for moderate ED
and 10% for complete ED (Feldman, Goldstein, Hatzichris-
tou, Krane, & McKinlay, 1994). ED occurs at an earlier age
in men with diabetes than in men in the general population
(Whitehead & Klyde, 1990), and its frequency has been
reported to be higher in people with diabetes compared with
those without diabetes in some but not all studies (Fairburn,
McCulloch, & Wu, 1982; Malgrange, Coulon, & Leuteneg-
ger, 1990; Miccoli et al., 1987). ED in diabetic men has
been associated with diabetic neuropathy (Saenz de Tejada
& Goldstein, 1988), peripheral vascular disease (Braunstein,
1987), poor glycemic control (McCulloch, Young, Prescott,
Campbell, & Clarke, 1984), use of specific types of med-
ications (Muller, El-Damanhoury, Ruth, & Lue, 1991;
Wiles, 1992), and increased age (McCulloch et al., 1984).
In response to sexual stimulation, nonadrenergic non-
cholinergic nerves and endothelial cells of the arterioles in
the penis release nitric oxide. This in turn stimulates the
formation of cyclic 3V,5V-guanosine monophosphate (cGMP)
by guanylate cyclase. cGMP then affects the relaxation of
the smooth muscles of the corpora cavernosa. cGMP is
hydrolyzed by cGMP-specific phosphodiesterase type 5
(PDE 5), the predominant PDE isoenzyme of the corpus
cavernosum (Boolell, Allen, Ballard, et al., 1996). Sildenafil
is a potent and competitive inhibitor of the PDE 5.
Sildenafil has been shown to be an effective and well-
tolerated treatment in patients with ED of various etiologies
1056-8727/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved.
doi:10.1016/S1056-8727(03)00056-4
* Tel.: +98-21-245-4499; fax: +98-21-245-6845.
E-mail address: mersa_mum@hotmail.com (M.R. Safarinejad).
Journal of Diabetes and Its Complications 18 (2004) 205–210

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(Boolell, Gepi-Attee, Gigell, & Allen, 1996; Goldstein et al.,
1998). This study was designed to determine if sildenafil
administered orally in single doses effectively and safely
improved penile erections in diabetic men with ED.
2. Materials and methods
2.1. Study design and patient population
Two hundred eighty-two diabetic men entered the study
(mean age 46 years, range 36–68) with a mean duration of
penile ED of 3.6 years (range 2.5–12). None of the patients
had received other treatment for male ED for at least 4
weeks before the start of the study. All participants provided
written informed consent. Exclusion criteria (Table 1)
included penile anatomical defects; a primary diagnosis of
another sexual disorder, major hematological, renal or
hepatic illnesses; any major psychiatric disorder not well
controlled with treatment; treatment with nitrates or andro-
gens; coronary artery disease; a history of stroke or myo-
cardial infarction, peptic ulcer disease; poorly controlled
diabetes mellitus; a history of alcohol or drug abuse; spinal
cord injury; hypotension (a resting blood pressure of <90/
50 mmHg) or hypertension (a resting systolic blood pressure
>170 mmHg or a resting blood pressure>100 mmHg;
proliferative retinopathy or autonomic neuropathy; and
history of ketoacidosis in the previous 2 years. Patients
were eligible for inclusion in the study if they were aged 18
years or older, had medically documented ED to be of at
least 6 months duration. The patients had to be in a stable
relationship with a female partner for at least the previous 6
months. The medical management of patients’ diabetes had
to be stable for at least 3 months prior to screening, with a
hemoglobin AlCvalue of less than 0.12 and a fasting plasma
glucose level of no more than 200 mg/dl at screening.
Male ED has been defined as the inability to attain and/or
maintain penile erection sufficient for satisfactory sexual
performance (NIH Consensus Conference, 1993).
Patients meeting inclusion criteria had their medical
histories and demographic information recorded (Table 2).
Age, marital status, weekly alcohol consumption, vascular
disease of the lower extremities, coronary heart disease,
nephropathy, autonomic and motor-sensory neuropathy,
diabetic foot, retinopathy, other medical history, and current
use of medications were recorded. The patients underwent a
full physical examination, which included blood pressure
and heart rate measurements, a 12-lead electrocardiogram,
standard biochemistry and hematological laboratory tests,
and measurement of serum testosterone and prolactin levels.
Men with low testosterone or elevated prolactin levels were
not eligible for enrolment.
At baseline (Week 0), the patients were randomly
assigned to take placebo or 100 mg of sildenafil citrate
(Viagra, Pfizer), 1 h prior to sexual activity but not more
than once daily, during the 16-week treatment period. The
placebo tablet was a starch compound with the same color
and size of the sildenafil citrate. All of the men were asked
not to consume alcoholic drinks within 6 h of sexual
activity. Each eligible patient was given a randomization
number using an interactive voice response system, which
followed a randomization table generated by the method of
random permuted blocks (Fleiss, 1986). Persons who geo-
graphically and operationally were independent from the
study investigator did the randomization of the study.
2.2. Outcome measures
The efficacy of the placebo and sildenafil was assessed
using responses to the questions from the self-adminis-
tered International Index of Erectile Function (IIEF), a
Table 1
Inclusion and exclusion criteria of the patients to the trial
Exclusion criteriaInclusion criteria
1. Penile anatomical defect
2. History of priapism
3. History of prostatectomy
4. Primary diagnosis of
another sexual disorder
5. Major hematological, renal, or
hepatic illness
6. Any major psychiatric disorder
7. Treatment with nitrates
8. Coronary artery disease
9. History of stroke or MI
10. Peptic ulcer disease
11. Poorly controlled diabetes mellitus
12. History of alcohol or drug abuse
13. Hypotension (BP <90/60 mmHg)
14. Uncontrolled hypertension
(BP >170/100)
15. Proliferative retinopathy
16. Autonomic neuropathy
17. History of ketoacidosis
in the previous 2 years
1. Aged 18 years or older
2. Documented ED for at
least 6 months
3. Stable relationship with a
female partner for at least
the previous 6 months
4. Hb A1cvalue<0.12 and
FBS<200 mg/dl for at least
3 months prior to screening
5. Normal serum testosterone
and prolactin levels
Table 2
Patients demographics (n=282)
Variables
Sildenafil citrate
(n=144)
Placebo
(n=138)
Mean age, years (range)
Mean duration of ED, years (range)
ED etiology, number (%)
Organic
Mixed organic/psychogenic
Mean duration of diabetes, years
Type of diabetes, number (%)
1
2
Concomitant medication
ACE inhibitors without diuretics
ACE inhibitors with diuretics
Diuretics
h-Blockers
46 (37–68)
3.6 (2.5–11)
46 (35–68)
3.9 (2.5–13)
139 (96.5%)
5 (3.5%)
11
132 (95.6%)
6 (4.4%)
11
26 (18%)
118 (82%)
22 (16%)
116 (84%)
30 (21%)
32 (22%)
18 (12.5%)
6 (4%)
31 (22.5%)
32 (23%)
15 (11%)
6 (4%)
ED=erectile dysfunction; ACE=angiotensin converting enzyme.
M.R. Safarinejad / Journal of Diabetes and Its Complications 18 (2004) 205–210
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15-question, validated measure of ED (Rosen et al., 1997):
Question 3, ‘‘When you attempted sexual intercourse, how
often were you able to penetrate your partner?’’ and Question
4, ‘‘During sexual intercourse, how often were you able to
maintain your erection to completion of intercourse?’’
Responses to the two questions were rated on a scale ranging
from 1 to 5, with five response options: 1=almost never/
never, 2=a few times (much less than half the time),
3=sometimes (approximately half the time), 4=most times
(much more than half the time), and 5=almost always/
always. The five separate response domains, erectile func-
tion, orgasmic function, sexual desire, intercourse satisfac-
tion,andoverallsatisfaction,werealsousedintheassessment
of efficacy. Each patient also responded to a global efficacy
question (‘‘Did the treatment improve your erections?’’) and
maintained an event log, in which was recorded the date of
the medication taken, the presence of sexual stimulation,
the hardness of erections on a 4-point scale, the number of
attempts at sexual intercourse, and the number of attempts
that were successful. The logs were reviewed at 0, 2, 4, 8, 12,
and 16 weeks. Adverse events were recorded at each visit
and laboratory tests were monitored throughout the study.
2.3. Statistical analysis
Analysis was performed according to the intention to
treat. All analyses of significance were two-sided and tested
at the 5% level; values of P<.05 were considered to
indicate significant differences. Qualitative variables were
compared with the use of chi-square test with Yates correc-
tion or Fisher’s exact test, when necessary. The Mann–
Whitney test was used to compare quantitative variables.
Statistical analysis was performed using the computer stat-
istical package SPSS/4.0 (SPSS, Chicago, IL) and SAS/6.4
(SAS Institute Cary, NC).
3. Results
All patients were seen with their partners and interviewed
about their sexual activity and patient’s erectile function.
Two hundred eighty two patients were recruited, but only
262 (93%) completed the whole randomized trial study (134
of 144 in the sildenafil group and 128 of 138 in the placebo
group) (Fig. 1). At baseline, the study and placebo groups
were similar in demographic and clinical characteristics
(Table 2). The majority of patients (83%) had Type 2
diabetes, were between the age of 48 and 60 years, and had
ED for several years. The median number of doses taken as
needed was 42 (range, 5–102) for patients receiving silde-
nafil and 40 (range, 4–97) for patients receiving placebo.
3.1. Efficacy
All patients took their medication between 2000 and
2300 h. Treatment with sildenafil was associated with
significantly higher scores for Question 3 (frequency of
penetration) and Question 4 (maintenance of erection after
sexual penetration) than baseline (P<.002) (Table 3). For
Question 3, the mean score was 2.8 for patients in the
sildenafil group compared with 2.2 for those in placebo
group, which represent increases from baseline of 55.5%
(mean score at baseline, 1.8) and 29% (mean score at
baseline, 1.7), respectively. For Question 4, the mean score
was 2.9 (61% increase from baseline mean score of 1.8) for
the sildenafil group compared with 2 (25% increase from
baseline mean score of 1.6) for the placebo group. At the
16-week end point, 68 (51%) of 134 patients taking silde-
nafil reported positive clinical results compared with 14
(11%) of 128 patients in the placebo group (P<.003). Fifty-
nine percent of the patients reported at least one successful
attempt at sexual intercourse in the sildenafil group as
compared with 21% successful attempts during placebo
treatment (P<.002). Data from patients’ event logs showed
no evidence of a treatment-period effect. Mean scores for
Fig. 1. Study design. GEQ, Global efficacy question; IIEF, international
index of erectile function.
Table 3
Mean (S.E.) scores for Questions 3 and 4 of the IIEF questionnaire at
baseline and at the end of the 16-week trial
Question 3Question 4
Baseline
Sildenafil
Placebo
1.8 (0.2)
2.8 (0.2)*
2.2 (0.2)
1.7 (0.2)
2.9 (0.2)*
2.0 (0.2)
* P<.002 vs. baseline.
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207

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the remaining 13 questions of the IIEF are shown in Table 4.
Scores are based on a scale of 1 to 5, with a higher score
indicating a more favorable outcome. For Questions 1, 2,
and 5 through 10, a score of 0 represented no activity or
intercourse. The mean scores for IIEF Questions 11 and 12,
which assessed frequency of sexual desire and rating of
sexual desire, respectively, indicated no statistically signific-
ant differences between the two groups (P=.75 and P=.2,
respectively). The remaining 11 questions assessing other
aspect of male sexual function showed significant improve-
ments for the sildenafil group compared with the placebo
group (P<.05). The efficacy of treatment in various sub-
groups of patients was also analyzed and is shown in
Table 5. Sildenafil significantly improved erectile function
across all three efficacy variables regardless of patient age,
the duration of ED, and the duration of diabetes (P<.002
vs. placebo for all three variables). Each of these three
efficacy variables demonstrated a significant improvement
Table 4
Mean scores to Questions 1, 2, and 5 through 15 of the IIEF at baseline and after 16 weeks of treatment with sildenafil or placebo
Mean score
Sildenafil citrate
(n=144)
Placebo
(n=138)
Overall
treatment
Question BaselineFinala
P value BaselineFinala
P valueb
P valuec
1. How often were you able to get an
erection during sexual activity?
2. When you had erection with sexual stimulation,
how were your erections hard enough for penetration?
5. During sexual intercourse, how difficult was it to
maintain your erection to completion of intercourse?
6. How many times have you attempted sexual intercourse?
7. When you attempted sexual intercourse,
how often was it satisfactory for you?
8. How much have you enjoyed sexual intercourse?
9. When you had sexual intercourse, how often did you ejaculate?
10. When you had sexual intercourse,
how often did you have the feeling of orgasm or climax?
11. How often have you felt sexual desire?
12. How would you rate your level of sexual desire?
13. How satisfied have you been with your overall sex life?
14. How satisfied have you been with your sexual relationship?
15. How do you rate your confidence that you could get and keep an erection?
2.1 3.0 (0.2)<.0022.02.0 (0.2).10<.002
1.82.9 (0.2) <.0021.7 1.9 (0.2) .82<.002
1.4 2.6 (0.2)<.002 1.3 1.6 (0.2) .20<.002
2.0
1.7
3.2 (0.2)
3.0 (0.3)
<.001
<.001
1.9
1.6
2.8 (0.2)
1.7 (0.3)
<.001
.31
<.001
<.001
1.7
2.7
2.8
2.7 (0.2)
3.7 (0.2)
3.8 (0.2)
<.001
<.002
<.002
1.6
2.8
2.7
1.8 (0.2)
3.3 (0.2)
3.1 (0.3)
.53
.50
.44
<.001
<.002
<.003
3.6
3.3
1.8
2.4
1.7
3.6 (0.2)
3.4 (0.1)
2.8 (0.2)
3.2 (0.2)
2.6 (0.2)
.97
.09
3.5
3.3
1.8
2.5
1.6
3.6 (0.2)
3.4 (0.1)
2.2 (0.2)
2.8 (0.2)
1.7 (0.2)
.50
.92
.003
.03
.07
.75
.20
<.001
<.001
<.001
<.001
.002
<.001
aLeast squares mean (S.E.) scores.
bP values for comparison between baseline and final scores.
cP values for overall treatment effect.
Table 5
Analysis of efficacy variables in subgroups of subjects at the end of trial
Question 3 mean (S.E.) scoreQuestion 4 mean (S.E.) scoreGlobal efficacy question, % yes
Subgroup (no. of patients) SildenafilPlaceboSildenafil Placebo SildenafilPlacebo
Duration of diabetes, years
0–5 (40; 39)
5–10 (41; 40)
>10 (53; 49)
3.6 (0.4)
2.3 (0.5)
2.8 (0.3)
2.2 (0.4)
1.7 (0.5)
1.8 (0.3)
3.1 (0.4)
2.3 (0.4)
3.0 (0.3)
1.2 (0.3)
1.6 (0.4)
2.1 (0.43)
61
51
50
9
14
12
Type of diabetes, years
1 (26; 22)
2 (118; 116)
2.9 (0.5)
3.1 (0.3)
2.1 (0.5)
2.1 (0.3)
2.8 (0.4)
3.0 (0.3)
2.0 (0.4)
1.8 (0.3)
51
52
19
11
Duration of ED, years
0–3 (52; 44)
3–6 (44; 41)
>6 (38; 43)
3.8 (0.4)
3.2 (0.4)
3.3 (0.3)
2.8 (0.4)
2.2 (0.3)
2.2 (0.3)
2.9 (0.4)
3.1 (0.3)
3.0 (0.4)
1.7 (0.3)
1.8 (0.4)
1.9 (0.3)
55
59
49
12
12
13
Age, years
18–49 (28; 28)
50–64 (75; 71)
z65 (31; 29)
3.4 (0.4)
3.3 (0.3)
3.1 (0.3)
2.4 (0.4)
2.4 (0.3)
1.6 (0.3)
3.4 (0.4)
3.0 (0.4)
3.0 (0.3)
2.2 (0.4)
1.9 (0.3)
1.6 (0.3)
61
55
51
10
13
10
The number of patients is indicated as follows: (sildenafil group; placebo group).
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with sildenafil treatment in patients with Type 2 diabetes
(P<.002 vs. placebo) and in patients with Type 1 diabetes
(P<.003 vs. placebo). Glycated hemoglobin, blood pres-
sure, etiology of ED, and age of subjects who responded to
sildenafil were similar to those found in patients who did not
respond to sildenafil.
3.2. Adverse effects
Adverse effects related to treatment were noted in 22%
(32/144) of patients taking sildenafil and 1.4% (2/138) of
patients taking placebo (Table 6) (P<.001). Of the patients
taking sildenafil, 20% reported headache as an adverse
event vs. 2% of patients taking placebo; 19% taking sil-
denafil reported flushing vs. 0% taking placebo; 9% taking
sildenafil reported dyspnea vs. 2% taking placebo; and 6%
taking sildenafil reported rhinitis vs. 0% taking placebo. The
overall incidence of cardiovascular adverse effects other
than flushing occurred in 7% (10/144) of patients taking
sildenafil vs. 0% of patients taking placebo. In the sildenafil
group, four patients had new chest pain of whom two
manifested an ST segment elevation > 3 mm with docu-
mented myocardial infarction. Other cardiovascular events
in the sildenafil group were two congestive heart failures
and four hypertensions. In patients with chest pain and
congestive heart failure, the treatment with sildenafil was
discontinued. Two patients (1.4%) who complained of
severe headache on sildenafil also discontinued the treat-
ment. One episode of prolonged erection was reported by
two (1.4%) men. No case of priapism was reported. The
reasons for discontinuation of treatment are listed in Fig. 1.
There was no significant change in laboratory tests.
4. Discussion
The increased frequency of impotence in the male
diabetic has long been recognized and has a multifactorial
etiology that includes psychogenic factors, autonomic neu-
ropathy, vascular disease, and drug intake. Several studies
have demonstrated a high prevalence (35% to 75%) of ED
in diabetic men (McCulloch, Campbell, Wu, Presscor, &
Clarke, 1980; Rubin & Babbott, 1958; Zemel, 1988).
Sildenafil is a novel, orally active agent that has long-
term efficacy and safety in treating men with ED of mixed
etiology (Chiristiansen, Guirguis, Cox, et al., 2000). The
approved and worldwide availability of sildenafil has fos-
tered exciting innovative research reports from independent
investigators around the world. Our investigation considered
the efficacy of sildenafil treatment in a group of diabetic
patients. Sildenafil was associated with a significant
increase, with respect to baseline, in the mean-end-of-
treatment scores for Questions 3 and 4 of the IIEF. In
addition, 51% of patients taking sildenafil reported that
treatment had improved their erections compared with only
11% of those taking placebos. We found that men with
diabetes had a lower response rate to sildenafil than that
previously reported in mixed, largely nondiabetic popula-
tions. Diabetic men may have sex hormone abnormalities
that could interfere with their response to sildenafil, but
serum testosterone and prolactin levels were measured in all
the men with diabetes who were screened for our study.
Men with low testosterone or elevated prolactin levels were
excluded from the study.
Penile erection is a complex neurovascular phenomenon
involving coordinated hemodynamic events and the inter-
action of nerves, neurotransmitters, striated and smooth
muscles, and the tunica albuginea. In diabetic men, ED
can result from any alteration in these components. Nitric
oxide released by the nonadrenergic noncholinergic nerve
terminals is believed to be the principal neurotransmitter
for penile erection. After entering the penile smooth
muscle cell, nitric oxide stimulates guanylate cyclase to
produce cyclic guanosine monophosphate, which relaxes
penile smooth muscle and produces penile erection. Type 5
phosphodiesterase is an enzyme that breaks down cyclic
guanosine monophosphate to guanosine monophosphate.
Sildenafil inhibits type 5 phosphodiesterase and thus
increases penile response to sexual stimulation. Sildenafil
does not produce or enhance erections unless the patient is
sexually stimulated and the production of cyclic guanosine
monophosphate inside the penis is increased. Impaired nitric
oxide synthesis may be an important factor in diabetic
patients with ED. Furthermore, advanced glycosylated prod-
ucts, which accumulate in tissue proteins, have been shown
to decrease nitric oxide activity and to modulate endothe-
lium-dependent relaxation, possibly via regulation of penile
nitric oxide synthase isozymes (Seftel, Vaziri, Ni, et al.,
1997). Reduction of nitric oxide synthesis and therefore
reduction of cyclic guanosine monophosphate in the smooth
muscle cells may cause submarginal effect of sildenafil in
diabetic patients. The lower response rate to sildenafil in our
study is consistent with previous studies. Rendell, Rajfer,
Wicker, and Smith (1999), in a well-designed study, found
56% improved erection in diabetic men taking sildenafil
compared with 10% of patients taking placebo. Leopore and
Nosari (2001) reported that of all the attempts at sexual
intercourse, 48.7% were successful during sildenafil treat-
ment. Neither of these two studies explains their findings
that men with diabetes had a lower response rate to
sildenafil than that previously reported in nondiabetic men.
Of importance is a high prevalence of cardiovascular
events with sildenafil. From patients in the sildenafil group,
Table 6
Adverse effects of sildenafil and placebo
Adverse effectsSildenafil citratePlacebo
Headache
Flushing
Dyspnea
Rhinitis
Cardiovascular
29 (20%)
27 (19%)
13 (9%)
9 (6%)
10 (7%)
3 (2%)
0 (0%)
3 (2%)
0 (0%)
0 (0%)
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