Inclusion Criteria:

• Type 2 diabetes mellitus treated with diet, oral hypoglycaemic agents or insulin) for a minimum of 2 years (24 months)
• Systolic hypertension prior to entry into the washout period. At Visit 3 patients must have a mean sitting systolic blood pressure in the range of 140-180 mmHg, and a mean sitting diastolic blood pressure <110mmHg
• A mean daytime ambulatory systolic blood pressure greater than or equal to 135 mm Hg at baseline

Exclusion Criteria:

• Poorly controlled type 2 diabetes mellitus (HbA1c ≥ 10%)
• Secondary hypertension of any aetiology, such as renal artery stenosis, coarctation of the aorta or pheochromocytoma
• History of malignant hypertension
• Body mass index > 37
• Single functioning kidney
• Known sensitivity or intolerance to angiotensin-converting enzyme inhibitors
• History of angioedema
• Known syncopal disorder
• Pregnant woman or a woman of childbearing potential who is sexually active and not using an appropriate method of birth control (double barrier or oral contraceptives)
• Concomitant therapy with any antihypertensive medications, including those used for indications other than hypertension (e.g., diuretics for any reason, minoxidil for hair loss, propranolol HCl for migraine, terazosin HCl for benign prostatic hyperplasia, 5-phosphodiesterase inhibitors (Viagra, Cialis, Levitra) within 48 hours of clinic visit, ACE-inhibitors for congestive heart failure, or any agent which could cause a change in blood pressure), except for stable doses of NSAIDs, or tricyclic agents taken at bedtime. Patients who are unwilling to discontinue these medications or patients in whom the Investigator feels it is clinically inappropriate to discontinue these medications should not participate in the study
• Concomitant therapy with lithium and/or major psychotropic agents such as phenothiazines
• Concomitant therapy with oral steroids or ACTH
• Concomitant therapy with cold and/or flu medications containing sympathomimetic agents. Intermittent use of therapies containing ephedrine is permitted except within 72 hours of clinic visits for mean trough SiSBP
• Concomitant therapy with any vitamin supplement that may contain pyridoxine or pyridoxine derivative such as pyridoxal phosphate or pyridoxal
• Hypertension induced by oral contraceptives. Replacement hormones (thyroid, testosterone, estrogens) are permitted if the patient has been on a stable dose for at least three months
• Existing symptomatic cerebro-vascular disease including previous transient ischemic attack (TIA) or stroke within 12 months prior to screening
• Myocardial infarction, percutaneous coronary intervention and coronary artery bypass surgery within 6 months prior to screening
• Clinically significant AV conduction disturbance, i.e., second or third degree AV block, sick sinus syndrome or clinically significant bradycardia (resting heart rate < 60 beats/minute) without a permanent pacemaker
• Presence of atrial flutter or atrial fibrillation
• Potentially life-threatening ventricular arrhythmias, decompensated valvular disease, presence of hemodynamically significant obstructive valvular disease, or cardiomyopathy
• Serum potassium < 3.5 or > 5.5 mEq/L
• The presence of severe hepatic impairment as manifested by AST (SGOT) > 2.5 times the upper limit of normal or ALT (SGPT) > 2.5 times the upper limit of normal
• Any clinically significant laboratory value which in the Investigator’s judgement could be clinically significant to the outcome of this study.

This includes, but is not limited to, hematocrit, haemoglobin or platelet count

• Any moderate to severe renal impairment, as manifested by serum creatinine more than 200 micromol/L
• A history of clinically important gastrointestinal resection, malabsorption or cirrhosis of the liver
• Any concurrent severe disease that, in the Investigator’s judgement, could preclude participation or survival
• Use of any investigational drug or device, or participation in any drug study during or within 30 days prior to baseline
• Inability to be taken off of all current antihypertensive medications
• Unwillingness or inability to give consent or to follow the protocol procedures
• Arm circumference greater than 41 cm