The purpose of this study is to compare the pharmacological profile of insulin administered with jet-injection with that of insulin injected with a conventional insulin pen.

Inclusion Criteria:

• Age 18-50 years
• Body-mass index 18-28 kg/m2
• Blood pressure <160/90 mmHg
• Stable glycaemic control with HbA1c 6.5-9.0% (for patients with type 1 diabetes mellitus)
• Duration of diabetes >1 year (for patients with type 1 diabetes mellitus)

Exclusion Criteria:

• Inability to provide informed consent
• Chronic use of medication other than oral contraceptives or thyroid hormone replacement therapy (with stable euthyroidism for at least 3 months)
• Chronic use of medication other than insulin or low-dose angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) treatment (for patients with type 1 diabetes mellitus)
• Type 2 diabetes in first-degree relatives (for healthy subjects)
• History of a major cardiovascular disease event (myocardial infarction, stroke, symptomatic peripheral artery disease, coronary bypass surgery, percutaneous coronary or peripheral artery angioplasty)
• Pregnancy
• Macroalbuminuria, i.e. urinary albumin excretion >200 microg/min in collected urine sample or urinary albumin-to-creatinine ratio >300 mg/g in spot urine sample (for patients with type 1 diabetes mellitus)
• Symptomatic diabetic neuropathy (for patients with type 1 diabetes mellitus)
• Proliferative diabetic retinopathy (a history of proliferative retinopathy that was successfully treated with laser coagulopathy is not an exclusion criterion) (for patients with type 1 diabetes mellitus)