• Intercourse success rate based on Event Logs [ Time Frame: continuous ] [ Designated as safety issue: No ]
• Ability to obtain an erection hard enough to attempt sexual intercourse post dose of sildenafil [ Time Frame: continuous ] [ Designated as safety issue: No ]
• Responses to the Self-Esteem And Relationship (SEAR) Questionnaire (including individual domain scores for the Sexual Activity, Self-Esteem And Relationship domains) [ Time Frame: Week 16 ] [ Designated as safety issue: No ]
• Responses to International Index of Erectile Function (IIEF) and secondary IIEF Domain scores (Orgasm; Desire; Intercourse Satisfaction; Overall Satisfaction) [ Time Frame: Week 16 ] [ Designated as safety issue: No ]
• Reponses to the Global Efficacy Assessment Questions [ Time Frame: Week 16 ] [ Designated as safety issue: No ]
• Flow mediated brachial artery dilation (FMD) as an index of generalized endothelial function [ Time Frame: Week 4, 6, and 16 ] [ Designated as safety issue: No ]

To determine the effect on erectile function in a population of type 2 diabetic men with erectile dysfunction who have undergone the following treatment regimen: pre-treatment with a daily dose of double-blind sildenafil versus placebo for 4 weeks (Phase I) followed by an as-needed, flexible-dose, open-label treatment phase with sildenafil for 12 weeks (Phase II). To assess safety and tolerability of this dosing regimen and to investigate its effects on endothelial function and subject's responses to the Self-Esteem And Relationship (SEAR) questionnaire.

• Erectile Dysfunction
• Diabetes Mellitus, Type 2

• Drug: sildenafil
• Drug: placebo

Inclusion Criteria:

Patients had a documented clinical diagnosis of erectile dysfunction, a sexual partner for the duration of the study, and have a HbAlc of less than or equal to 10 at screening. Type 2 diabetic patients currently on insulin or on combination therapy with an oral hypoglycemic agent were not excluded.

Exclusion Criteria:

Excluded were subjects who had taken more than 6 doses of any PDE5 inhibitor and/or had taken their last dose less than 4 weeks prior to the screening visit; subjects with resting sitting and/or standing hypotension (BP < 90/50mmHg) or hypertension (BP > 170/110mmHg); and subjects with significant cardiovascular disease, including cardiac failure, myocardial infarction, unstable angina, stroke or transient ischemic attack (TIA), symptomatic or clinically significant cardiac arrhythmias including atrial fibrillation in the last 3 months.