Endogenous Insulin Secretion Ability in Meal Tolerance Test Is Correlated with Body Mass Index (BMI)

Endogenous Insulin Secretion Ability in Meal Tolerance Test Is Correlated with Body Mass Index (BMI) [Objective] Several studies re [Objective] Several studies report that endogenous insulin secretion (EIS) ability is correlated with BMI in glucagon loading tests. Despite a standard method to assess EIS, glucagon loading tests can produce side effects such as nausea. Therefore, we investigated the relationship between EIS and BMI with a simple meal tolerance test.[br][Method] 100 type 2 diabetes mellitus (DM) patients (average: age 61, male 56/female 44, HbA1c 9.2%, BMI 25.0, duration of DM 11.5 years) admitted to Tottori University Hospital from 2009 to 2010 were examined and subjected to a meal tolerance test. We measured serum C-peptide immunoreactivity (CPR) at fasting and two hours after a calorie controlled breakfast (ideal body weight*30kcal/day), and calculated the difference to give [Delta]CPR. (Treatment; diet alone 17, oral hypoglycemic agent (OHA) only 51, insulin only 14, OHA+insulin 18).[br][Results] The fasting and postprandial CPR were significantly correlated with BMI (R=0.59, R=0.48, P[lt]0.0001, respectively). [Delta]CPR was also significantly correlated to BMI (R=0.34, P[lt]0.001). The mean BMI of 9 patients with [Delta]CPR [lt]1 was significantly lower compared with that of [Delta]CPR [gt]=1 (BMI 19.0 vs. 25.6). The fasting plasma glucose (FPG) was not significantly correlated to [Delta]CPR, but HbA1c had a significant negative association of [Delta]CPR (R=-0.38, P[lt]0.0005). The optimal cut-off level of BMI to predict [Delta]CPR [lt]1 was 20.5 using the ROC curve (sensitivity 83%, specificity 88%). Using multiple regression analysis, we examined influence factors of [Delta]CPR. The independent variables were: age, gender, BMI, FPG, HbA1c, Cr, duration of DM, having OHA or not, having insulin injection or not. The significant standard partial regression coefficients were: BMI 0.254, insulin use -0.237, HbA1c -0.358 (P[lt]0.05).[br][Conclusion] The BMI significantly was correlated with insulin secretion ability in a meal tolerance test. We speculate BMI is a simple and beneficial index to predict EIS ability. It is noteworthy that the insulin secretion ability diminished in patients with BMI [lt]20 and high HbA1c.

Correlation to BMI	Fasting CPR	Post prandial CPR	ΔCPR
correlation coefficient R	0.59 (P<0.0001)	0.48 (P<0.0001)	0.34 (P<0.001)

TSUYOSHI OHKURA, SHIN-ICHI TANIGUCHI, SHOICHIRO IZAWA, KEISUKE SUMI, YOUHEI FUJIOKA, NAOYA YAMAMOTO, KAZUHIKO MATSUZAWA, HIDEKI SHIOCHI, HIROSHI KINOSHITA, CHIAKI SHIGEMASA 2557-PO Yonago, Japan, Yonago, Tottori Prefecture, Japan, Yonag, Japan Insulin Action - Metabolism