I agree that your results warrant some changes; be it life style, eating, supplemetation or worst-case, using a mild prophylactic Rx med (like Glucophage/Metformin) if things get progress or do not improve (but these come with their own problematic issues).
I also agree that being even mildly insulin-resistant can thwart fat loss. That said, 10% is extremely lean in the bigger scheme of things so adopting and maintianing a rationale perspective when addressing this would be prodent.
EBF is pretty much the authority around here on all things insulin related/glucose intolerance issues. Hit him up or post this query in the EBF Formulations section. There are a myriad of sensible supplementing strategies available to you OTC so I'd utilize these in advance of medicating.