2 questions: 1- should you take a drug to prevent DM
2- which drug
1: If you have another risk factor, and are trending higher, then I would recommend trying a drug. Risk factors include a family history of DM, and/or a high sugar after you eat a meal, i.e. over 140 2 hours after. And since you are losing weight, you could wait @ 3 months and recheck fasting sugar- if trending down, I would hold off on a drug.
2: If you are at higher risk and trending up, drugs can prevent DM (although can cause other problems...). If you are relatively young (<40) and very heavy (BMI > 36), I would recommend metformin, unless liver or kidney problems. If you are not so overweight, actos is good as well, unless you have congestive heart failure. The difference is that metformin will help you lose weight, but actos does not.
Overall, actos can help prevent diabetes, but like any drug can cause other problems. You sound like you are a good patient, so keep up with the diet and exercise. I would only use a drug if you are doing 'the right stuff', but your numbers don't improve. Best of luck and remember- we're all prediabetic if we live long enough :)