I suffer from acanthrosis nigricans on my underarms and groin only. i got checked for diabetes, but it was normal. could i just be insulin resistant?

Acanthosis: is a common indicator of insulin resistance. You may not have diabetes yet, but it's a gradual progression from obesity to insulin resistance to glucose intolerance to prediabetes to diabetes. It's all the same disease, no matter what name you give it. Lose weight now.

Causes of AN: There are many causes of AN, not just DM2 although the latter is most common. Insulin resistance is a precursor to DM2 and as such, PCOS may also be associated with AN. Similarly, other causes of insulin resistance as Cushing's, acromegaly and hypothyroidism can result in AN. Nicotinic substances may also cause AN. A rare cause is familial. The most concerning cause is cancer esp GI tumors.