No diabetes mellitus currently treated with insulin or sulfonylureas Patients with known pre-existing diabetes mellitus will be excluded from study Patients with diabetes mellitus requiring concurrent treatment with insulin or thiazolidinedione (TZD) oral agents are not eligible Insulin dependent diabetes mellitus For Part G: Have type 1 diabetes mellitus or a history of gestational diabetes mellitus. Participants with a type 2 diabetes mellitus are eligible if adequate control of blood glucose level is obtained with oral therapy as documented by Hemoglobin A1c <7%. Patients with known pre-existing diabetes mellitus Patients with diabetes mellitus requiring insulin treatment or uncontrolled steroid-induced diabetes mellitus Patients with insulin-dependent diabetes mellitus Have insulin-dependent diabetes mellitus or a history of gestational diabetes mellitus. Poorly controlled Type 2 diabetes mellitus Presence of poorly controlled diabetes mellitus (glycated hemoglobin [HgbA1c] > 9.0%). Patient has poorly controlled diabetes mellitus or steroid-induced diabetes mellitus Insulin-dependent diabetes mellitus (patients with type 2 diabetes controlled with oral glucose lowering agents and the occasional use of insulin are permitted in the study) DONOR: Diabetes mellitus Poorly controlled diabetes mellitus Insulin-dependent diabetes mellitus. Diabetes mellitus Diabetes mellitus. Patient has poorly controlled diabetes mellitus or steroid-induced diabetes mellitus Insulin-dependent diabetes mellitus Patient has clinically manifest diabetes mellitus for the last 3 months or documented steroid-induced diabetes mellitus. Patient with poorly controlled diabetes mellitus or documented steroid-induced diabetes mellitus (defined as FPG > 140 mg/dL or Hemoglobin A1C (HbA1C) > 7.8) Uncontrolled diabetes mellitus with most recent hemoglobin A1C > 9 performed in last 6 months; this requirement is for subjects with known history of diabetes mellitus only Subjects with documented history of diabetes mellitus except for the Diabetes\n Expansion Cohort Patients with diabetes mellitus are eligible if they require oral agents only and have a fasting blood glucose =< 120 mg/dL; patients with a history of diabetes mellitus who require daily long-acting or mealtime insulin are not eligible; patients who have previously required treatment for hyperglycemia due to steroids or other medications are eligible as long as they have not required insulin or any other oral agent within 2 months prior to study enrollment Subject has clinically manifest diabetes mellitus or documented steroid-induced diabetes mellitus Patients with diabetes mellitus requiring insulin treatment and/or with clinical signs or with FPG > 140 mg/dL or history of documented steroid-induced diabetes mellitus Poorly controlled diabetes mellitus Diabetes mellitus currently requiring insulin; subjects with a history of steroid-induced hyperglycemia may be enrolled provided that HbA1C at screening visit is =< 8% Patients with clinical manifestation of uncontrolled diabetes mellitus (i.e. treated and/or with clinical signs) or steroid-induced diabetes mellitus Poorly-controlled diabetes mellitus (DM) Patient with diabetes mellitus that is suboptimally controlled (fasting plasma glucose >= 140, glycosylated hemoglobin > 7.0) despite oral medication, insulin-dependent diabetes, or documented steroid-induced diabetes mellitus Have insulin-dependent diabetes mellitus. Participants with type 2 diabetes mellitus are eligible if adequate control of blood glucose level is obtained by oral anti-diabetics as documented by hemoglobin A1c (HbA1c) <7%. Patients with diabetes mellitus requiring concurrent treatment with insulin or thiazolidinedione (TZD) oral agents are not eligible Have insulin-dependent diabetes mellitus or a history of gestational diabetes mellitus. Patient has poorly controlled diabetes mellitus with a glycosylated hemoglobin > 8% or poorly controlled steroid-induced diabetes mellitus with a glycosylated hemoglobin of > 8% Patient with clinically manifest diabetes mellitus, or documented steroid induced diabetes mellitus Patient has poorly controlled diabetes mellitus or steroid-induced diabetes mellitus Diabetes mellitus Patients with diabetes mellitus requiring insulin treatment and/or with clinical signs or with FPG >= 140 mg/dL/7.8 mmol/L, or history of documented steroid-induced diabetes mellitus are not eligible for participation Patients with a history of diabetes mellitus (DM) and/or patients who have ever been treated with metformin are not eligible for participation Patient has poorly controlled diabetes mellitus or steroid-induced diabetes mellitus (hemoglobin A1C [HbA1C] > 7.5%) Patients with clinically manifest diabetes mellitus (treated and/or clinical signs or with fasting glucose >= 140 mg/dL / 7.8 mmol/L), history of gestational diabetes mellitus or documented steroid-induced diabetes mellitus Diabetes mellitus Patients with brittle diabetes mellitus (DM); brittle diabetes mellitus is a type of diabetes when a person's blood glucose (sugar) level often swings quickly from high to low and from low to high; also called \unstable diabetes\ or \labile diabetes\ Poorly controlled diabetes mellitus Diabetes mellitus For all Arms, patients with poorly controlled diabetes mellitus and/or with clinical signs, and/or steroid-induced diabetes mellitus; for Arm B, patients requiring insulin treatment History of gestational diabetes mellitus Diabetes mellitus Diabetes mellitus History of insulin-dependent or uncontrolled Diabetes Mellitus Subjects with diabetes mellitus requiring insulin treatment or subjects with a HbA1C > DONOR: History of diabetes mellitus Have insulin-dependent diabetes mellitus. Participants with a type 2 diabetes mellitus are eligible if adequate control of blood glucose level is obtained by oral anti-diabetics. Has poorly controlled diabetes mellitus defined as HbA1c > 6.5%. Patient has poorly controlled diabetes mellitus (defined as hemoglobin A1C [HgA1c] > ULN), steroid-induced diabetes mellitus or insulin dependent diabetes mellitus Diabetes mellitus currently requiring insulin or insulinotropic therapy or prior history of steroid induced diabetes. Patients with diabetes mellitus Have insulin-dependent diabetes mellitus. Participants with a type 2 diabetes mellitus are eligible if adequate control of blood glucose level is obtained by oral anti-diabetics as documented by hemoglobin A1c <7%. Any patient with known diabetes mellitus currently requiring insulin therapy, or any patient with preexisting diabetes mellitus in poor control, defined as a hemoglobin A1C (HbA1C) value of over 9% within 4 weeks of starting therapy Patients with poorly controlled diabetes mellitus, steroid-induced diabetes mellitus, HbA1c > 7%, or FPG > 7.0 mmol/L (125 mg/dL). Diabetes mellitus that is not controlled with medication Clinically manifest diabetes mellitus, history of gestational diabetes mellitus and/or known glucose intolerance. Patients with diabetes mellitus requiring insulin treatment and/or with clinical signs or with fasting glucose ? 140 mg/dL / 7.8 mmol/L, history of clinically significant gestational diabetes mellitus or documented steroid-induced diabetes mellitus Unstable diabetes mellitus. Poorly controlled diabetes mellitus or active, steroid-induced diabetes mellitus Must not have poorly controlled diabetes mellitus, known central nervous system involvement by malignant disease or insufficient bone marrow, renal, or hepatic function Patients with diabetes mellitus; (patients with only a history of gestational diabetes will be allowed to be included in the study) Patient has poorly controlled diabetes mellitus (HbA1c > 8%) Poorly controlled diabetes mellitus; Diabetes mellitus Diabetes mellitus is not exclusionary provided the patient is not maintained with either oral medications or insulin The participant has diabetes mellitus as defined by being treated with glucose lowering medications in the past 3 months prior to enrollment. d. Poorly controlled diabetes mellitus (HbA1C >10.0%); The participant has poorly controlled diabetes mellitus. Participants with a history of diabetes mellitus are allowed to participate, provided that their fasting glucose < 160 mg/dL or below the ULN and that they are on a stable dietary or therapeutic regimen for this condition Diabetes mellitus Actively uncontrolled diabetes mellitus (documentation of history of diabetes mellitus [DM] with A1c > 8) Diabetes mellitus Insulin dependent diabetes mellitus (DM) and/or metformin use History of diabetes mellitus or a neurological disorder that causes distal symmetric polyneuropathy Patients must not have a history of macular edema, uveitis or diabetes mellitus Endocrine disorders such as primary aldosteronism, pheochromocytoma, hyper- or hypothyroidism not controlled with medication, or insulin dependent diabetes mellitus Patient has poorly controlled diabetes mellitus with a glycosylated hemoglobin > 8% or poorly controlled steroid-induced diabetes mellitus with a glycosylated hemoglobin of > 8% Participant has known diabetes mellitus - insulin treated Patients with diabetes mellitus requiring insulin secretagogues and/or insulin No history of diabetes mellitus or stroke, or bleeding tendency Subjects may have diabetes mellitus History of diabetes mellitus Patients with clinically manifest diabetes mellitus (treated and/or clinical signs or with fasting glucose ? 126 mg/dL / 7.0 mmol/L or hemoglobin A1c >6.5%), history of gestational diabetes mellitus or documented steroid-induced diabetes mellitus. History of diabetes mellitus Poorly controlled diabetes mellitus Have diabetes mellitus NORMAL VOLUNTEERS: Have diabetes mellitus Poorly controlled diabetes mellitus (defined as HbA1c > 9%) Subjects with insulin dependent diabetes mellitus.