The study is designed to compare meal time glucose control associated with BIOD-531, a rapidly absorbed concentrated insulin to that associated with Humalog Mix 75/25 and Humulin R U-500 in patients with diabetes and severe insulin resistance.

Inclusion Criteria:

• BMI > 25 kg/m2
• Diabetes Mellitus using ≥ 150 units of insulin or insulin analog per day and/or ≥ 100 units of insulin or insulin analog at a single dosing session for at least 1 month prior to screening
• HbA1c < 10.0%

Exclusion Criteria:

• History of bariatric surgery
• Corticosteroid therapy
• Significant cardiovascular or other major organ disease
• Females who are breast feeding or pregnant
• A sexually active person not using adequate contraceptive methods