Please assess the completion status of the following clinical trial:

Trial Title: Metformin and Congenital Nephrogenic Diabetes Insipidus

Study Design Characteristics:
- Allocation: None
- Intervention Model: SINGLE_GROUP
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: NONE
- Phase: PHASE1
- Number of Arms: 1.0

Eligibility Criteria:
Inclusion Criteria:~* Males with a documented mutation in the vasopressin type 2 receptor (V2R)~* Willing to provide consent and/or assent as appropriate~* Capable of providing urine samples as dictated by the protocol~Exclusion Criteria:~* Urinary incontinence~* Subjects who have heart disease, liver disease, diabetes, cancer, or other significant disease other than Nephrogenic Diabetes Insipidus (NDI)~* Subjects with significant renal dysfunction (defined as a calculated glomerular filtration rate (GFR) \<80 ml/min/1.73 m\^2)~* Subjects with acquired NDI

- Gender: MALE
- Minimum Age: 18 Years
- Maximum Age: None
- Healthy Volunteers: f

Study Arms:
- Metformin (Type: EXPERIMENTAL): Subjects with congenital nephrogenic diabetes insipidus (NDI) will receive one metformin 500 mg pill orally

Based on this trial design, predict the completion outcome and termination type (if applicable).