Factors influencing insulin sensitivity during hyperinsulinemic-euglycemic clamp in healthy Korean male subjects

Figures & data

Table 1 Baseline demographic and clinical characteristics of subjects who completed the hyperinsulinemic euglycemic clamp

	Young group (n=10)^a	Elderly group (n=13)^a	P-value^b
Age (year)	23±3 (13.1)	57±7 (11.5)	<0.001
Body weight (kg)	69.2±7.7 (11.1)	67.1±3.5 (5.2)	0.445
BMI (kg/m^2)	22.6±1.6 (7.3)	23.2±1.3 (5.6)	0.372
Fat mass (kg)	12.0±2.9 (24.4)	15.9±3.5 (21.9)	0.010
Fat free mass (kg)	57.1±6.6 (11.5)	51.2±3.2 (6.3)	0.021
Skeletal muscle mass (kg)	32.2±3.7 (11.6)	28.5±2.0 (7.1)	0.006
Body fat (%)	17.3±3.6 (20.5)	23.7±4.5 (19.1)	0.002
Waist–hip ratio	0.84±0.05 (5.5)	0.89±0.04 (4.1)	0.010

Notes: ^aValues are presented as arithmetic mean ± SD (CV, %).

^bP<0.05 was considered significantly different between the two age groups.

Abbreviations: BMI, body mass index; CV, coefficient of variation; OGTT, oral glucose tolerance test.

Table 2 Baseline clinical characteristics and parameters of insulin sensitivity under hyperinsulinemic euglycemic clamp at 80 mU/m²·min

Parameters	Young group (n=10)^a	Elderly group (n=13)^a	P-value^b
Baseline insulin (mU/L)	10.8±6.0 (55.8)	8.3±3.2 (39.0)	0.250
Baseline C-peptide (ng/mL)	1.2±0.5 (38.6)	1.2±0.2 (20.5)	0.721
Fasting glucose (mg/dL)	93.0±6.6 (7.1)	95.4±6.1 (6.4)	0.380
Glucose (mg/dL) at 2 hours during OGTT	104.4±15.2 (14.6)	106.2±29.7 (28.0)	0.867
AST (U/L)	22.6±9.2 (40.7)	26.8±11.2 (41.8)	0.351
ALT (U/L)	21.0±16.4 (78.1)	22.2±9.5 (42.6)	0.823
ALP (U/L)	68.1±33.7 (49.5)	62.7±12.9 (20.6)	0.640
GGT (U/L)	17.0±4.8 (28.1)	31.8±13.6 (42.7)	0.002
Total cholesterol (mg/dL)	165.0±28.6 (17.3)	198.4±29.5 (14.9)	0.013
TG (mg/dL)	96.7±49.6 (51.3)	115.5±51.9 (44.9)	0.391
HDL (mg/dL)	64.6±10.8 (16.7)	51.3±10.1 (19.7)	0.006
LDL (mg/dL)	89.9±24.1 (26.8)	123.2±13.6 (42.7)	0.005
HbA1c (%)	5.2±0.2 (3.6)	5.4±0.3 (5.2)	0.029
M-value (mg/kg body weight·min)	10.8±3.6 (32.8)	9.9±2.7 (27.5)	0.458
M-value (mg/kg FFM· min)	13.1±4.1 (31.3)	12.9±3.5 (27.3)	0.900
Matsuda index	6.4±2.7 (43.0)	5.2±1.6 (29.8)	0.248
HOMA-IR	1.6±0.6 (39.7)	1.3±0.3 (23.7)	0.185

Notes: ^aValues are presented as mean ± SD (CV, %). ^bP<0.05 was considered significantly different between two age groups.

Abbreviations: ALT, alanine transaminase; AST, aspartate transaminase;  CV, coefficient of variation; GGT, gamma-glutayltransferase; HbA1c, hemoglobin A1c; HDL, high-density lipoprotein; HOMA-IR, homeostasis model assessment of insulin resistance; LDL, low-density lipoprotein; FFM, fat-free mass; OGTT, oral glucose tolerance test; TG, triglyceride.

Table 3 Correlation of M-value normalized by fat-free masswith insulin, C-peptide and 2-hour glucose in oral glucose tolerance test according to age groups

Parameters	Young group (n=10)	Elderly group (n=13)	Total (n=23)
Baseline insulin
r	−0.353	−0.619	−0.418
P-value^a	0.318	0.024	0.047
Baseline C-peptide
r	−0.400	−0.520	−0.426
P-value^a	0.252	0.069	0.043
Two-hour glucose level during oral glucose tolerance test
r	−0.167	−0.627	−0.452
P-value^a	0.644	0.022	0.030

Note: ^aSignificant correlation was considered at P<0.05.

Figure 1 Inverse relationship of M-value normalized by FFM with (A) baseline insulin (r=−0.418, P=0.047), (B) baseline C-peptide (r=−0.426, P=0.043) and (C) glucose at 2 hours during OGTT (r=−0.452, P=0.030).

Abbreviations: FFM, fat-free mass; OGTT, oral glucose tolerance test.

Table S1 Correlation of M-value normalized by body weight with insulin, C-peptide and 2-hour glucose in OGTT according to age groups

Parameters	Young group (n=10)	Elderly group (n=13)	Total (n=23)^a
Baseline insulin
r	−0.344	−0.593	−0.360
P-value^a	0.330	0.033	0.092
Baseline C-peptide
r	−0.418	−0.557	−0.435
P-value^a	0.229	0.048	0.038
Two-hour glucose level during oral glucose tolerance test
r	−0.173	−0.568	−0.395
P-value^a	0.634	0.043	0.062

Note: ^aSignificant correlation was considered at P<0.05

Table S2 Glucagon and GLP-1 related parameters during OGTT

Parameters	Young group^a	Old group (n=10)^a	Correlation with MBW-value^b	Correlation with MFFM-value^b
Baseline glucagon (pmol/L)	–	8.8±6.3 (71.8)	0.011 (0.976)	−0.030 (0.935)
Cmin of glucagon (pmol/L)	–	2.8±2.7 (97.2)	0.137 (0.707)	0.089 (0.807)
AUC of glucagon (pmol·h/L)	–	547.3±450.6 (82.3)	−0.030 (0.934)	−0.006 (0.987)
Baseline active GLP-1 (pmol/L)	–	7.8±7.2 (92.6)	−0.455 (0.187)	−0.503 (0.138)
Cmax of active GLP-1 (pmol/L)	–	11.9±9.1 (76.5)	−0.079 (0.829)	−0.152 (0.676)
AUC of active GLP-1 (pmol·h/L)	–	1118.9±783.6 (70.0)	−0.152 (0.676)	−0.212 (0.556)
Baseline total GIP (pmol/L)	–	23.6±18.5 (78.1)	0.304 (0.393)	0.292 (0.413)
Cmax of total GIP (pmol/L)	–	415.2±173.6 (41.8)	0.361 (0.305)	0.420 (0.226)
AUC of total GIP (pmol·h/L)	–	38,351.9±16,783.0 (43.8)	0.248 (0.489)	0.224 (0.533)

Notes: ^aPlasma levels of glucagon, active GLP-1, and total GIP were measured in 10 subjects in the elderly group. ^bValues are presented as correlation coefficient (P-value) and significant correlation was considered at P<0.05.

Abbreviations: GIP, glucose-dependent insulinotropic polypeptide; GLP-1; glucagon-like peptide-1, OGTT, oral glucose tolerance.

Data availability

The datasets generated during the current study are available from the corresponding author on reasonable request.