Type 2 diabetes mellitus is a chronic metabolic disorder characterized by progressive deterioration in the function of the pancreatic beta-cells, which are the cells that produce and secrete insulin (the hormone primarily responsible for the handling of glucose in the body). The investigators propose a randomized controlled trial to determine whether intermittent intensive insulin therapy is an effective therapeutic strategy that can preserve pancreatic beta-cell function and maintain glycemic control early in the course of type 2 diabetes.

In this study, eligible patients with type 2 diabetes will be randomized to either intermittent insulin therapy or not, on a background of metformin, after first undergoing a short course of intensive insulin therapy. The hypothesis under study is whether intermittent insulin therapy can preserve beta-cell function.

Inclusion Criteria:

1. Men and women between the ages of 30 and 80 years inclusive
2. T2DM diagnosed by a physician </= 5 years prior to enrolment
3. Negative for anti-glutamic acid decarboxylase (anti-GAD) antibodies
4. On either no anti-diabetic medication or on metformin monotherapy, with no change in dose/regimen within 4 weeks prior to enrolment
5. A1c at screening between 5.5% and 9.0% inclusive if on metformin, or between 6.0% and 9.5% inclusive if on no oral anti-diabetic medication
6. BMI >/= 23 kg/m2
7. Negative pregnancy test at recruitment for all women with childbearing potential

Exclusion Criteria:

1. Current anti-diabetic treatment with insulin, sulfonylurea, thiazolidinedione, alpha-glucosidase inhibitor, glucagon-like peptide-1 (GLP-1) agonist or dipeptidyl peptidase-4 inhibitor
2. Type 1 diabetes or secondary forms of diabetes
3. History of hypoglycemia unawareness or severe hypoglycemia requiring assistance
4. Any major illness with a life expectancy of <5 years
5. Hypersensitivity to insulin, metformin or the formulations of these products
6. Renal dysfunction as evidenced by estimated glomerular filtration rate (eGFR) <50 ml/min
7. Hepatic disease considered to be clinically significant (includes jaundice, chronic hepatitis, previous liver transplant) or transaminases >2.5 X upper limit of normal
8. History of congestive heart failure
9. Excessive alcohol consumption, defined as >14 alcoholic drinks per week for males and >9 alcoholic drinks per week for females
10. Unwillingness to administer insulin therapy or perform capillary blood glucose monitoring at least 4 times per day while receiving IIT
11. Pregnancy or unwillingness to use reliable contraception. Women should not be planning pregnancy for the duration of the study or the first 3 months after the study. Reliable contraception includes birth control pill, intra-uterine device, abstinence, tubal ligation, partner vasectomy, or condoms with spermicide.
12. Non-adherence to the induction phase or any factor likely to limit adherence to the study protocol, in the opinion of the investigator