Please assess the completion status of the following clinical trial:

Trial Title: Metformin in Amnestic Mild Cognitive Impairment

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: PREVENTION
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE2
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion criteria:~* Age range: 55 years to 90 years. The main rationale for this inclusion criteria is to follow the standard set by the Alzheimer's Disease Cooperative Study (ADCS).~* Memory complaint expressed by the participant and recognized by the informant. The memory complaint must represent a change from previous functioning based on information provided by both subject and informant.~* Fluent in English or Spanish.~* Mini-Mental State Examination (MMSE) equal or more than 20.~* Subjects must fulfill criteria for amnestic mild cognitive impairment (MCI). Guidelines for the diagnosis of MCI: Subjects must score below a predetermined cut-off score on the logical memory II delayed paragraph recall sub-test of the Wechsler Memory Scale Revised (WMS-R) or the selective reminding test (SRT).~* Global Clinical Dementia Rating (CDR) score must be 0.5 at screening.~* Subjects without a known history of diabetes or diabetes that has never been treated with medications. If diabetes is diagnosed during screening or they have a history of diabetes not treated in the last 12 months they will be excluded if their Hemoglobin A1c (HbA1c) is \> 6.5. In addition, a diagnosis of diabetes can be made if the HbA1c is 6.5% or more.~* Overweight or obese by National Heart, Lung, and Blood Institute (NHLBI) criteria (Body Mass Index (BMI) of more or equal of 25 kg/ m2).~* No contraindications to metformin treatment.~* Hachinski score less or equal to 4.~* Hamilton score less or equal to 12 on the 17 item scale.~* General cognition and functional performance such that a diagnosis of dementia cannot be made at the time of screening based on DSM-IV criteria.~* Vision and hearing must be sufficient for compliance with testing procedures.~Exclusion criteria:~* Individuals with dementia~* MMSE \< 20~* Subjects with neurologic diseases associated to neurologic deficits.~* Subjects with current psychiatric diagnoses such as depression, bipolar disorder or schizophrenia.~* Subjects with uncontrolled hypertension (systolic blood pressure more than 160 mmHg or diastolic blood pressure more than 95 mmHg.~* Subjects with a history of active cancer or cancer within last five years, with the exception of squamous or basal cell carcinoma of the skin.~* Subjects who for any reason may not complete the study as judged by the study physician.~* Subjects with a known history of diabetes treated with medications.~* Subjects with a new or old diagnosis of diabetes, never treated, with a HbA1c of more than 6.5 .~* Contraindications to metformin: Contraindications to metformin use include a creatinine of \> 1.5, liver disease by history or by elevated transaminases, congestive heart failure, and alcohol abuse.~* Use of cholinesterase inhibitors.~Exclusion criteria for brain imaging study:~* Presence of diabetes, even if the HbA1c is less or equal to 6.5.~* Inability to lie down for any reason.~* Presence of any metallic implant.~* Claustrophobia.~* Any contraindication to magnetic resonance imaging (MRI) or fluorodeoxyglucose (FDG) positron emission tomography (PET).

- Gender: ALL
- Minimum Age: 55 Years
- Maximum Age: 90 Years
- Healthy Volunteers: f

Study Arms:
- Matching Placebo (Type: PLACEBO_COMPARATOR): Placebo identical to metformin
- Metformin (Type: EXPERIMENTAL): Metformin 1000 mg twice a day

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