(A and B) The body composition of age- and sex-matched mutant and control mice was analyzed. Ngn3Δint mice have approximately 30% less body fat (A), are leaner (B), and show an improved BMI (C) compared with control mice. (D) Control (filled squares) and mutant (filled circles) mice were fasted and subjected to an ITT. Mutant mice show improved insulin sensitivity, seen also by the reduction in the average under the curve between 0–45 minutes after insulin injection (AUC, left inset). In addition, mutant mice show a clear difference in the fasting blood glucose level (right inset). n = 6–7. *P < 0.05, **P < 0.01.