The relationship between age of onset and risk factors including family history and life style in Korean population with type 2 diabetes mellitus.

The study analysed 969 of 2,610 initially selected patients because missing data were excluded, including 751 missing family history. People were already diagnosed with type 2 diabetes, and risk factors were taken from charts after diagnosis, so the study cannot show that any factor caused earlier onset. Lifestyle and body mass index were measured at the time of the examination, not immediately after diagnosis, so weight and habits may have changed after diagnosis. Exercise was recorded only as yes or no, with no dose, intensity or timing, and the authors suggest the exercise association may reflect post-diagnosis behaviour. Family history categories combined parents and siblings, so the separate effects of mother, father and siblings may not be clean. The sample was limited to Korean outpatients already receiving blood sugar control, so it may not apply to undiagnosed people or other populations.

This study was supported by a grant from the Korean Diabetes Association and Korean Association of Diabetes Nurse Educators.

Do not conclude that exercise causes earlier type 2 diabetes. Exercise was measured after diagnosis, and the study only reported an association, not a tested effect.