Fig. 1Changes in plasma glucose (A), insulin (B), and glucagon (C), insulin-to-glucose ratio (D), glucagon-to-insulin ratio (E) and percent change of glucagon-to-insulin ratio (F) response during 75-g oral glucose tolerance test (OGTT) before and after sitagliptin treatment. Values are presented as mean±standard error. (Glucagon/insulin) %change=100×[(glucagon/insulin at 30, 60, 90, or 120-minute)-(glucagon/insulin at 0 minute)]/(glucagon/insulin at 0 minute). Open circles and dashed lines indicate measures before sitagliptin treatment; closed squares and solid lines indicate measures after sitagliptin treatment. "P for trend" indicates the comparison of time course curves during OGTT, analyzed by repeated measures analysis of variance. aP<0.05 at the 0, 30, 60, 90, or 120-minute time points using Wilcoxon signed rank test for paired values.
Table 1Baseline clinical characteristics
Characteristic |
Baseline |
Number |
24 |
Age, yr |
53.75±2.11 |
Sex, male:female |
14:10 |
Weight, kg |
62.45±2.10 |
Height, cm |
164.37±1.57 |
BMI, kg/m2
|
23.05±0.62 |
HbA1c, % |
7.22±0.26 |
Duration of diabetes, yr |
5.83±5.18 |
Total cholesterol, mmol/L |
4.15±0.13 |
Triglyceride, mmol/L |
3.27±0.71 |
HDL-C, mmol/L |
1.31±0.07 |
LDL-C, mmol/L |
2.21±0.11 |
AST, IU/L |
23.57±2.42 |
ALT, IU/L |
24.45±2.80 |
Table 2Changes in β-cell function and insulin sensitivity after 6 months of sitagliptin treatment
|
Baseline (n=24) |
After treatment (n=24) |
P value |
Glucose, mmol/L |
|
|
|
0 min |
9.10±0.64 |
8.62±0.58 |
0.209 |
120 min |
16.52±0.89 |
15.08±1.03 |
0.072 |
Insulin, pmol/L |
|
|
|
0 min |
45.21±5.36 |
52.36±7.64 |
0.361 |
120 min |
148.62±21.27 |
234.06±29.88 |
0.001 |
C-peptide, nmol/L |
|
|
|
0 min |
0.68±0.09 |
0.63±0.36 |
0.695 |
120 min |
1.94±0.17 |
1.91±0.98 |
0.760 |
Glucagon, ng/L |
|
|
|
0 min |
72.73±3.54 |
79.54±17.32 |
0.140 |
120 min |
74.07±3.26 |
82.47±21.06 |
0.120 |
Total AUC (insulin/glucose) |
8.76±1.53 |
15.01±2.04 |
0.001 |
HOMA-IR |
2.78±0.39 |
3.09±0.70 |
0.797 |
Matsuda index |
6.37±0.96 |
5.22±0.73 |
0.317 |
Insulinogenic index |
0.63±0.11 |
1.18±0.27 |
0.001 |
HOMA-β |
26.95±3.31 |
33.57±4.15 |
0.061 |
Total AUC (glucagon/insulin) |
1.95±1.09 |
1.56±1.03 |
0.303 |
HbA1c, % |
7.22±0.26 |
6.96±0.20 |
0.098 |
Table 3Subgroup analysis according to the initial BMI and HbA1c
|
Baseline |
After treatment |
P value |
BMI <23 (n=13) |
|
|
|
Total AUC (I/G) |
11.26±2.43 |
17.52±3.12 |
0.034 |
HOMA-IR |
1.78±0.42 |
2.24±0.42 |
0.116 |
Matsuda index |
7.96±1.46 |
5.27±0.73 |
0.152 |
Insulinogenic index |
0.83±0.16 |
1.46±0.48 |
0.082 |
HOMA-β |
26.46±4.29 |
36.86±4.44 |
0.046 |
HbA1c, % |
6.57±0.26 |
6.38±0.13 |
0.357 |
BMI ≥23 (n=11) |
|
|
|
Total AUC (I/G) |
7.51±1.51 |
11.26±2.26 |
0.007 |
HOMA-IR |
3.96±0.49a
|
4.09±1.43 |
0.594 |
Matsuda index |
4.49±0.98a
|
5.15±1.38 |
0.929 |
Insulinogenic index |
0.49±0.13a
|
0.83±0.15 |
0.005 |
HOMA-β |
27.52±5.38 |
29.67±7.45 |
0.689 |
HbA1c, % |
7.98±0.36a
|
7.64±0.31 |
0.166 |
HbA1c <7% (53 mmol/mol) (n=11) |
|
|
|
Total AUC (I/G) |
12.51±2.64 |
17.52±1.89 |
0.092 |
HOMA-IR |
1.70±0.34 |
2.28±0.49 |
0.075 |
Matsuda index |
7.13±1.09 |
5.40±0.84 |
0.110 |
Insulinogenic index |
0.83±0.19 |
1.11±0.17 |
0.152 |
HOMA-β |
33.66±5.24 |
42.69±6.68 |
0.110 |
HbA1c, % |
6.19±0.15 |
6.27±0.14 |
0.722 |
HbA1c ≥7% (53 mmol/mol) (n=13) |
|
|
|
Total AUC (I/G) |
6.26±1.04a
|
12.51±3.11 |
0.003 |
HOMA-IR |
3.69±0.55a
|
3.77±1.22 |
0.463 |
Matsuda index |
5.73±1.54 |
5.06±1.17 |
0.972 |
Insulinogenic index |
0.56±0.14 |
1.25±0.50 |
0.003 |
HOMA-β |
21.26±3.69a
|
25.85±4.31 |
0.294 |
HbA1c, % |
8.08±0.29a
|
7.54±0.27 |
0.031 |