My cholesterol is 172, HDL is 45, triglycerides 45, LDL is119. The general physician is suggesting statins. Is it necessary or not? (diabetes and RA, BP 105/65, weight 145).

Yes. Patients with diabetes are considered to be high risk for a heart attack. If you were my patient (or my relative), i would ask you start a low dose of a safe and cheap statin, such as pravastatin. Pravastatin 20 mg is generic and only rarely has side effects. The benefit would be lower your cholesterol, which may reduce your risk of a heart attack. An ldl-c of 100 is a reasonable goal of treatment.
Recommended. In patients with diabetes, the recommended level for LDL is below 100. If you are already doing a fairly good job of avoiding fats in your diet, then additional treatment, most commonly with a statin, would be recommended to bring your LDL down to the desired level.
Yes. Current guidelines recommend the use of statins for diabetics with a LDL of greater than 100. An optional goal of decreasing the LDL to less than 70 is usually set for those at particularly high risk.
Not necessary. Agree goal is <100 but should probably look at your average LDL over a few samples. Go to framingham risk calcluator on-line and play with your numbers to see what benefit you can expect from lowering LDL with statin. It is not impressive. Diet / exercise and wt loss may help a small bit.