my dad has been taking metformin for over a year and has recently had his dose doubled. he also takes meds for b.p. and cholesterol and has mild copd and sleep apnea. he has complained of increasing fatigue and that his arms and legs feel like "lead." i have noticed that metformin can cause lactic acidosis which could explain some of his symptoms. he sees a family practice md who has not done much to help figure out his distress. his fatigue has become so bad that he sleeps off and on throughout the day and has no energy. he is 70 years old and normally quite active. any ideas on how i can help my dad would be appreciated.