Irisin levels in patients with prediabetes mellitus: A case-control study and meta-analysis

Table 1 Baseline characteristics of the study participants

Characteristic	NGT (n = 26)	PreDM (n = 9)	P value
Demographics
Age (year)	32.00 (30.00, 32.00)	33.00 (28.00, 39.00)	0.810
Male	3 (11.5)	5 (55.6)	0.015
Anthropometrics
Body mass index (kg/m2)	22.11 (19.00, 23.00)	25.01 (23.00, 28.00)	0.001
Waist circumference (cm)	76.48 ± 7.63	94.03 ± 9.41	0.000
Hip circumference (cm)	97.00 (94.00, 98.30)	105.00 (99.00, 106.30)	0.003
Waist-to-hip ratio	0.79 ± 0.06	0.90 ± 0.06	0.000
Clinical status
Fatty liver	3 (11.5)	5 (55.6)	0.015
Family history of DM	7 (26.9)	4 (44.4)	0.416
Smoking status	0 (0)	1 (11.1)	0.257
Alcohol drinking status	4 (15.4)	4 (44.4)	0.162
Biochemical parameters
Irisin (ng/mL) ELK	5.79 (4.99, 6.07)	5.89 (5.06, 6.57)	0.985
Irisin (pg/mL) Elabscience	22.99 ± 8.90	30.59 ± 10.95	0.045
Glu0 (mmol/L)	4.95 ± 0.38	5.62 ± 0.53	0.000
Glu0.5 (mmol/L)	7.86 ± 0.31	10.24 ± 0.88	0.000
Glu1 (mmol/L)	6.83 ± 1.79	10.38 ± 1.97	0.000
Glu2 (mmol/L)	5.48 (4.81, 6.07)	7.84 (6.95, 8.17)	0.000
Glu3 (mmol/L)	4.35 (3.75, 4.81)	4.30 (3.82, 6.23)	0.697
Ins0 (μIU/mL)	8.67 (6.00, 11.00)	15.61 (11.00, 24.00)	0.001
Ins0.5 (μIU/mL)	90.96 (58.00, 142.00)	117.22 (55.00, 183.00)	0.540
Ins1 (μIU/mL)	92.64 (51.00, 153.64)	154.21 (92.00, 217.21)	0.056
Ins2 (μIU/mL)	49.37 (32.00, 81.37)	101.87 (58.00, 204.87)	0.001
Ins3 (μIU/mL)	25.95 (12.00, 41.95)	37.83 (22.00, 54.83)	0.271
CP0 (ng/mL)	1.80 (1.45, 2.00)	2.90 (2.32, 3.33)	0.000
CP0.5 (ng/mL)	8.30 (6.01, 10.43)	9.36 (5.89, 11.97)	0.838
CP1 (ng/mL)	9.29 (6.01, 15.83)	12.72 (9.28, 14.34)	0.079
CP2 (ng/mL)	7.92 ± 2.42	12.04 ± 3.39	0.000
CP3 (ng/mL)	5.24 ± 2.13	6.26 ± 2.06	0.221
GCG0 (pmol/L)	14.79 ± 6.42	20.41 ± 8.77	0.048
GCG0.5 (pmol/L)	5.83 ± 3.19	10.85 ± 3.31	0.000
GCG1 (pmol/L)	3.67 (2.00, 5.00)	6.68 (4.00, 7.00)	0.005
GCG2 (pmol/L)	3.74 (2.00, 5.00)	5.51 (3.00, 8.00)	0.061
GCG3 (pmol/L)	5.46 (2.00, 8.00)	11.06 (6.00, 24.00)	0.016

Data conforming to a normal distribution are presented as mean ± SD. Non-normally distributed data are presented as median (IQR). Categorical variables are presented as n (%). NGT: Normal glucose tolerance; PreDM: Prediabetes mellitus; DM: Diabetes mellitus; Glu0: Fasting blood glucose; Glu0.5: Oral glucose tolerance test 0.5-hour post-load blood glucose; Glu1: Oral glucose tolerance test 1-hour post-load blood glucose; Glu2: Oral glucose tolerance test 2-hour post-load blood glucose; Glu3: Oral glucose tolerance test 3-hour post-load blood glucose; Ins0: Fasting insulin; Ins0.5: Oral glucose tolerance test 0.5-hour post-load blood insulin; Ins1: Oral glucose tolerance test 1-hour post-load blood insulin; Ins2: Oral glucose tolerance test 2-hour post-load blood insulin; Ins3: Oral glucose tolerance test 3-hour post-load blood insulin; CP0: Fasting C-peptide; CP0.5: Oral glucose tolerance test 0.5-hour post-load blood C-peptide; CP1: Oral glucose tolerance test 1-hour post-load blood C-peptide; CP2: Oral glucose tolerance test 2-hour post-load blood C-peptide; CP3: Oral glucose tolerance test 3-hour post-load blood C-peptide; GCG0: Fasting glucagon; CGC0.5: Oral glucose tolerance test 0.5-hour post-load blood glucagon; GCG1: Oral glucose tolerance test 1-hour post-load blood glucagon; GCG2: Oral glucose tolerance test 2-hour post-load blood glucagon; GCG3: Oral glucose tolerance test 3-hour post-load blood glucagon.

Table 2 Correlation of irisin with other metabolic parameters

	r value	P value
Irisin (ng/mL) ELK	-0.183	0.294
Body mass index	0.185	0.286
Gender	-0.04	0.818
Age	-0.026	0.884
Waist circumference	0.098	0.577
Hip circumference	-0.054	0.757
Waist-to-hip ratio	0.203	0.241
Fatty liver	0.350	0.039
Family history of DM	0.152	0.382
Glu0	0.168	0.336
Glu0.5	0.421	0.012
Glu1	0.307	0.073
Glu2	0.154	0.377
Glu3	0.207	0.232
GCG0	0.045	0.796
GCG0.5	0.066	0.707
GCG1	0.009	0.961
GCG2	-0.044	0.802
GCG3	-0.076	0.664
Ins0	-0.032	0.857
Ins0.5	0.018	0.919
Ins1	-0.063	0.718
Ins2	0.028	0.874
Ins3	0.254	0.141
CP0	0.046	0.793
CP0.5	-0.007	0.969
CP1	-0.049	0.779
CP2	0.003	0.987
CP3	0.184	0.289
Smoking history	-0.136	0.437
Alcohol drinking history	0.101	0.564

DM: Diabetes mellitus; Glu0: Fasting blood glucose; Glu0.5: Oral glucose tolerance test 0.5-hour post-load blood glucose; Glu1: Oral glucose tolerance test 1-hour post-load blood glucose; Glu2: Oral glucose tolerance test 2-hour post-load blood glucose; Glu3: Oral glucose tolerance test 3-hour post-load blood glucose; Ins0: Fasting insulin; Ins0.5: Oral glucose tolerance test 0.5-hour post-load blood insulin; Ins1: Oral glucose tolerance test 1-hour post-load blood insulin; Ins2: Oral glucose tolerance test 2-hour post-load blood insulin; Ins3: Oral glucose tolerance test 3-hour post-load blood insulin; CP0: Fasting C-peptide; CP0.5: Oral glucose tolerance test 0.5-hour post-load blood C-peptide; CP1: Oral glucose tolerance test 1-hour post-load blood C-peptide; CP2: Oral glucose tolerance test 2-hour post-load blood C-peptide; CP3: Oral glucose tolerance test 3-hour post-load blood C-peptide; GCG0: Fasting glucagon; CGC0.5: Oral glucose tolerance test 0.5-hour post-load blood glucagon; GCG1: Oral glucose tolerance test 1-hour post-load blood glucagon; GCG2: Oral glucose tolerance test 2-hour post-load blood glucagon; GCG3: Oral glucose tolerance test 3-hour post-load blood glucagon.

Table 3 Subgroup analyses of irisin levels

Subgroup	Number of studies	SMD (95%CI)	P value	I2 (%)
By specimen type
Plasma	5	-0.769 (-1.304 to -0.234)	0.005	87.0
Serum	5	-0.282 (-0.826 to 0.263)	0.311	87.4
By ELISA kit manufacturer
Adipogen	3	-0.565 (-0.791 to -0.338)	< 0.001	0
CusabioTM	1	-0.533 (-0.915 to -0.151)	0.006
Bio Vision, Milpitas	1	-1.307 (-1.774 to -0.840)	< 0.001
Phoenix	1	0.517 (-0.047 to 1.082)	0.072
SinoGeneClon Biontec	1	-0.124 (-0.525 to 0.276)	0.542
USCN Life Science	1	-0.071 (-0.530 to 0.389)	0.763
Not specified (NO)	2	-1.116 (-3.388 to 1.155)	0.335	97.3
Overall	10	-0.524 (-0.897 to -0.152)	0.006	86.7

SMD: Standardized mean difference; 95%CI: 95% confidence interval; ELISA: Enzyme-linked immunosorbent assay.