Hi, welcome to healthcare magic There 2 main types of diabetes- type 1 which is mainly seen in children and occurs there is a lack of insulin and type 2 which occurs because the body is resistant to insulin. Type 2 is mainly seen in adults. In general the more body fat a person has , the more resistant to insulin, so weight loss, unless excessive actually aids in the management of diabetes by improving the body s response to insulin. Insulin is the only medication used at the present time to treat type 1 diabetes. In type 2 diabetes oral medication can also be used. The oral medications work by different mechanisms including - causing your body to secrete insulin if it still can, reducing resisitance to insulin and the newer medications like galvus- increase your feeling of fullnes and reduce empty of the stomach which are good things. Galvus met is actually not associated with weight loss unlike the other newer medications and this is actually considered a disadvantage. Less weight- less resistance to insulin. All medication have potential side effects , however it does not mean they are likely to be experienced.The potential side effects of galvus med include low blood sugar, nausea, headache. Since your father is not intentional losing weight and galvus met is not associated with weight loss,it would actually be best if he was reviewed by his doctor to determine if there is another reason for his weight loss. I hope this information is helpful to you and wish you both the best