Can someone who looks thin still have insulin resistance or prediabetes ("skinny fat")?

Yes, this is sometimes informally referred to as "skinny fat" or metabolically obese normal weight, where someone has a normal BMI but higher visceral fat (fat around internal organs) or lower muscle mass than expected, both of which affect insulin sensitivity. BMI alone doesn't capture body composition, which is exactly why relying on it as the only screening tool can miss people who are genuinely at risk despite looking thin. References: https://obesitycanada.ca/healthcare-professionals/adult-clinical-practice-guideline/ https://guidelines.diabetes.ca/GuideLines/media/Docs/Quick%20Reference%20Guide/2024-CPG-Quick-Reference-Guide.pdf

Was shocked honestly, always been thin and assumed that meant I was fine. Bloodwork said otherwise.