>> pelley: the c.d.c. says one in three americans has a blood digar level that raises their risk of diabetes. tonight, dr. jon lapook on what's called "prediabetes." te reporter: researchers at u.c.l.a. estimate nearly half of all adults in california have prediabetes or undiagnosed diabetes. that's 46% of all adults, 33% of young adults 18-39. >> the rates are very high, surprisingly high. >> reporter: researcher susan babey co-authored the report. ncree're very concerned about the rates among the young adults because of their increased risk on developing type 2 diabetes, which sets them on this path for some serious complications in the future. >> reporter: complications include blindness, heart and kidney disease, and premature thath. without intervention, about 70% al those with prediabetes eventually develop diabetes. thth intervention, it doesn't