lack of patients who meet inclusion criteria; there was one screen failure

The investigators hypothesize that in adult patients with diabetic gastroparesis with Type 1 diabetes (HbA1c ≤ 10.5%), daily tadalafil use will significantly improve gastric emptying compared to baseline as measured by gastric emptying time.

Inclusion Criteria:

• Type 1 diabetes diagnosis
• Age 18 - 65 years (inclusive)
• Hemoglobin A1c ≤ 10.5% within the last 4 months
• Diagnosis of gastroparesis, or symptoms consistent with gastroparesis (early satiety, chronic intermittent nausea or vomiting with food intake)
• Patient has gastroparesis confirmed on screening study
• A female patient is eligible to participate if she is of: Non-childbearing potential defined as pre-menopausal females with a documented tubal ligation or hysterectomy; or postmenopausal defined as 12 months of spontaneous amenorrhea, or child-bearing potential with negative serum hCG prior to each gastric emptying study.

Exclusion Criteria:

• Active nitrate use (e.g. Cialis, Viagra, Levitra, nitroglycerin, Isordil, Imdur, amyl nitrate/poppers)
• Fasting fingerstick glucose > 250 mg/dL
• History of abdominal surgery including gastric banding procedure
• Patient is on chronic parenteral feeding
• Patient has a history of eating disorders (anorexia nervosa, binge eating, bulimia)
• Regular opiate use
• Recent (last 6 weeks) history of poor control of diabetes e.g. hypoglycemia requiring medical intervention, diabetic ketoacidosis, admission for control diabetes or complications of diabetes
• Acute severe gastroenteritis
• The patient has participated in another clinical trial in the last 30 days.
• Use of medications potentially influencing upper gastrointestinal motility or appetite within one week of the study [e.g., prokinetic drugs, macrolide antibiotics (erythromycin), GLP-1 mimetics/analog, amylin analog]
• History or presence of clinically significant gastro-intestinal, hepatic or renal disease or other condition that would in the opinion of the investigator make the subject unsuitable for inclusion in this clinical study.
• Chronic angina or NYHA class III or IV CHF
• Concurrent use of ketoconazole or itraconazole
• History of severe vision loss, retinitis pigmentosa, or non-arteritic anterior ischemic optic neuropathy (NAION)
• History of CVA
• Pregnant females as determined by positive serum hCG test
• Lactating females
• Uncontrolled hypertension (SBP > 160 or DBP > 100)
• Hypotension (SBP < 90 or DBP < 60)
• Other major medical conditions: priapism, sickle cell anemia, multiple myeloma, leukemia, active cancer diagnosis, HIV/AIDS, alcoholism, or bleeding diathesis.
• Intolerance to active or inactive ingredients of Cialis, or intolerance to other PDE-5 inhibitors.