1663-P: Monophasic Glucose Response Curve Reflective of Glucose Intolerance in Young Mexican Americans

The glucose response curve of an oral glucose tolerance test (OGTT) has been associated with insulin sensitivity. A monophasic curve has been shown to be more prevalent in hyperglycemic and T2D population. However, it is unknown whether shape of curve in a healthy normoglycemic population can be indicative of risk for developing T2D.

Purpose: We aimed to determine if glucose response morphology, monophasic (M) versus biphasic (B), may be indicative of glucose tolerance and a family history of T2D (FH).

Methods: Normoglycemic Mexican American Males (mean ± SEM; age 23.26 ± 0.66 years, BMI 25.69 ± 0.97 kg/m²) with (n=7) or without (n=7) a FH participated in this study. Body composition was measured by DXA, substrate utilization was measured by indirect calorimetry, maximal aerobic capacity (VO₂max) was measured by a standardized graded exercise test. Participants consumed 75 g of glucose while fasting and blood glucose were assessed at 0, 30, 60, 90, and 120 min. Based on Tschritter et al. (2003) classification, glucose response curves were separated into M (n=10) and B (n=4) groups.

Results: There were no significant differences in body weight, BMI, fat mass, fat free mass, resting substrate utilization, VO₂max and fasting blood glucose (BG) between groups (all P > 0.05). However, M were significantly glucose intolerant compared to B evident by a greater glucose area under the curve (M: 263.63 ± 11.34 AU; B: 209.20 ± 4.46 AU; p=0.01) and a significantly greater BG levels during OGTT at minute 30 (149.97 ± 8.53 vs. 110.53 ± 12.60 mg/dl; p=0.02), 60 (149.80 ± 9.33 vs. 104.99 ± 17.21 mg/dl; p=0.03) and 90 (116.48 ± 6.62 vs. 71.71 ± 10.11 mg/dl; p< 0.01) compared to B. All individuals with a monophasic OGTT response had a FH whereas most individuals with biphasic OGTT response (7/10) did not.

Conclusion: Although having similar fasting BG, body composition, substrate utilization, and aerobic fitness, a monophasic compared to biphasic, OGTT reflects glucose intolerance and risk for developing T2D.