Blood sugar does not suddenly “break” at 40. For most people, the bigger issue is a slow shift: less muscle, more abdominal fat, changing hormones, poorer sleep, more medications, and years of habits adding up. That gradual change can make the body less sensitive to insulin, the hormone that helps move glucose from the blood into cells. The concern is real. The American Diabetes Association recommends routine diabetes screening for many adults starting at age 35, and earlier