T1DM for at least 5 years as defined by the following:

1. Insulin dependence (with an insulin requirement less than 0.8 units/kg/day).

2. Current or past anti-islet antibodies (anti-insulin before initiation of insulin therapy, anti-islet cell (ICA), anti-tyrosine phosphatase IA-2, and/or anti-glutamic acid decarboxylase (GAD65) antibodies).

3. BMI greater than or equal to 20 kg/m(2) and less than or equal to 30 kg/m(2).

C-peptide greater than or equal to 0.3 and less than or equal to 1.2 ng/mL at baseline or during an arginine-stimulated C-peptide test.

Age 18 to 60 years, inclusive.

Symptomatic gastroparesis.

Diabetic nephropathy with a creatinine clearance less than 60 cc/min or 24-hour urine albumin greater than 300 mg.

Insulin requirements greater than 0.8 units/kg/day.

Hypoglycemia unawareness: Unless easily corrected via simple modifications in the patient's diabetes regimen, the potential enrollee will be excluded if he/she has suffered greater than or equal to 2 episodes of severe hypoglycemia during the most recent 12 months, defined as requiring assistance from a third party, receiving assistance from medics, visiting an ER or being hospitalized due to the hypoglycemia.

Evidence of chronic infection.

History of any malignancy.

Any chronic medical condition that unduly increase risk for the potential enrollee as judged by study investigators.

Hematologic abnormalities:

1. Anemia (hematocrit less than 31.8% in women and less than 36.7% in men).

2. Leukopenia (WBC count less than 3.4 K/mm(3)).

3. Thrombocytopenia (platelet count less than 162 K/mm(3)).

Hypertension, whether untreated or resistant to medical treatment, with blood pressure greater than 140/85 mm Hg.

Pregnancy, breastfeeding or planned pregnancy within two years.

Unable to identify primary care provider willing to partner with study investigators.