Nombre_BBDD='test'
host='localhost'
puerto='5432'
usuario='postgres'
password='xxxxxxx'
Nombre_Tabla='table'
Llave_primaria='id'
Capa_a_procesar='/xxxxxxx/shapefile.SHP'
Tipo_geometria='POLYGON'

capaImportar = QgsVectorLayer(Capa_a_procesar, 'capaImportar', 'ogr')
uri = """dbname='"""+Nombre_BBDD+"""' host='"""+host+"""'    port="""+puerto+""" user='"""+usuario+"""' password='"""+password+"""' key="""+Llave_primaria+""" type="""+Tipo_geometria+""" table="public".""""+Nombre_Tabla+"""" (geom) sql="""
crs = QgsCoordinateReferenceSystem(25830)
error = QgsVectorLayerImport.importLayer(capaImportar, uri, "postgres", crs, False, True)

# su - postgres
$ psql
psql (8.4.17)
Digite «help» to get help.

postgres=#

postgres=# CREATE USER your_user WITH PASSWORD 'your_password' SUPERUSER;
CREATE ROLE
postgres=# CREATE DATABASE utah OWNER zeito;
CREATE DATABASE

import psycopg2

try:

    conn = psycopg2.connect(dbname='utah',
                            host='localhost',
                            port=5432,
                            user='zeito',
                            password='********')

except:
    print "I am unable to connect to the database"

cur = conn.cursor()

layer = iface.activeLayer()
feats = [feat for feat in layer.getFeatures()]
ls = feats[0].geometry().asWkb().encode('hex')

# Send it to PostGIS
cur.execute('CREATE TABLE route(geom geometry, name text)')
cur.execute(
    'INSERT INTO route(geom, name)'
    'VALUES (ST_SetSRID(%(geom)s::geometry, %(srid)s), %(name)s)',
    {'geom': ls, 'srid': 32612, 'name': 'route'})

conn.commit()  # save data

print "Done"