Impact of body mass index and age on the relative accuracy of self-reported energy intakes among Japanese patients with type 2 diabetes.

Dietary questionnaires have been used to ascertain food or nutritional intakes in many studies; however, the extent and characteristics of measurement errors in patients with diabetes have not been examined. This study examined the measurement errors from self-reported dietary history questionnaires (DHQ) in Japanese patients with type 2 diabetes (T2D). Fifty-nine patients with T2D underwent a 24-h urine collection and 3-day dietary record (DR), and completed the DHQ. Intakes of energy, protein, sodium, and potassium were calculated from the DHQ. The estimated energy intake was calculated from the DR, and estimated intakes of protein, sodium, and potassium were determined from the 24-h urine samples. Energy intake values from the DHQ were lower than those from the DR by 12.5% in men and by 14.6% in women, which was significant only in men. In women, protein intake values from the DHQ were 19% higher than those from the 24-h urine. Multivariable linear regression analysis showed that energy intake ratio (DHQ/DR) was significantly negatively associated with body mass index (BMI) in both sexes and significantly positively associated with age only in women (all  < 0.05). Protein intake ratio (DHQ/24-h urine) was positively associated with duration of diabetes only in men ( < 0.05); however, this relation disappeared in the multivariable model. No factors showed association with sodium or potassium intake ratio. The DHQ showed under-reporting of energy intake by approximately 15% in Japanese patients with T2D. This was associated with obesity in both sexes and with younger age in women.