Common side effects: affect 1 to 10 users in 100  Changes in the levels of some blood cells and circulating fats.  Increases in the level of sugars in the blood and urine.  Feeling more hungry.  Dizziness.  Restlessness.  Tremor.  Muscle stiffness or spasm (including eye movements).  Problems with speech.  Unusual movement (especially of the face or tongue).  Constipation.  Dry mouth.  Rash.  Loss of strength.  Extreme tiredness.  Water retention leading to swelling of the hands, ankles or feet.  In the early stages of treatment, some people may feel dizzy or faint (with a slow heart rate), especially when getting up from a lying or sitting position.