Circulating preptin levels in normal, impaired glucose tolerance, and type 2 diabetic subjects

Figures & data

Table I.  Clinical characteristics and preptin levels of study subjects. Data are mean±standard deviation or frequency (percentage).

Factor	NGT	IGT	T2DM
n	54	56	50
Age (years)	51±12	53±13	54±10
Weight (kg)	58±11	62±10	61±10
BMI (kg/m^2)	23.4±3.8	25.0±3.6^a	24.4±3.3
WHR	0.86±0.05	0.87±0.06	0.90±0.06^b,d
FAT (%)	31.2±7.2	33.7±6.6	30.6±7.8^c
SBP (mmHg)	121±18	125±14	127±16^a
DBP (mmHg)	76±8	78±8	78±10
TG (mmol/L)	1.38±0.89	1.73±0.83	2.06±1.26^b
TC (mmol/L)	4.47±0.94	4.54±1.04	4.79±1.01
HDL-C (mmol/L)	1.21±0.28	1.21±0.52	1.18±0.31
LDL-C (mmol/L)	2.64±0.69	2.67±0.69	2.73±0.79
FFA (µmol/L)	0.60±0.26	0.73±0.35^a	0.69±0.22
FBG (mmol/L)	5.4±0.4	5.7±0.5	9.3±3.7^b,d
2hOGTT (mmol/L)	6.3±1.0	9.1±0.9^b	18.4±6.8^b,d
FIns (mU/L)	9.6±5.0	9.49±4.4	11.2±7.2
2hIns (mU/L)	41.6±3.1	81.5±8.6^b	44.3±4.1^d
HbA1c (%)	5.5±0.4	6.0±0.5^b	8.7±2.5^b,d
HOMAIR	2.3±0.2	2.4±0.2	4.5±0.3^b,d
HOMAIS	108±8.4	100±9.3	60±8.6^b,d
Preptin (ng/L)	398±13	416±13	456±14^b,c

^a P < 0.05 compared with NGT.

^b P < 0.01 compared with NGT.

^c P < 0.05 compared with IGT group.

^d P < 0.01 compared with IGT group.

NGT = normal glucose tolerance; IGT = impaired glucose tolerance; T2DM = type 2 diabetes mellitus; BMI = body mass index; SBP = systolic blood pressure; DBP = diastolic blood pressure; WHR = waist-to-hip ratio; FAT (%) = the percentage of fat in vivo; FBG = fasting blood glucose; 2hOGTT = 2-h blood glucose after glucose overload; HOMA_IR=homeostasis model assessment-insulin resistance index; HOMA_IS=homeostasis model assessment-β-cell insulin secretion index; HbA₁c = glycosylated haemoglobin; FFA = free fatty acids; TG = triglyceride; TC = total cholesterol; HDL = high-density lipoprotein; LDL = low-density lipoprotein; FIns = fasting insulin; 2hIns = 2-h insulin.

Table II.  Linear and multiple regression analysis of variables associated with plasma preptin levels in subjects studied.

	Simple		Multiple
Variable	Estimate	P-value	Estimate	P-value
Age	−0.039	0.619	——	——
BMI	0.094	0.228	——	——
WHR	−0.061	0.437	——	——
FAT%	0.119	0.128	——	——
Systolic BP	0.027	0.731	——	——
Diastolic BP	0.197	0.007	1.876	0.024
Fasting glucose	0.022	0.118	——	——
2hOGTT glucose	0.180	0.023	——	——
Insulin	0.087	0.265	——	——
2hIns	−0.007	0.933	——	——
HOMAIR	0.130	0.045	——	——
HOMAIS	−0.027	0.73	——	——
HbA1c	0.189	0.008	——	——
Total cholesterol	0.241	0.002	——	——
Triglyceride	0.244	0.001	17.827	0.022
HDL-C	0.191	0.014	47.869	0.009
LDL-C	0.119	0.127	——	——
FFA	0.212	0.004	59.964	0.023

In multiple linear stepwise regression analysis, values included for analysis were age, gender, body mass index (BMI), waist-to-hip ratio (WHR), systolic blood pressure, diastolic blood pressure, fasting glucose, 2-h blood glucose after glucose overload (2hOGTT glucose), glycosylated haemoglobin (HbA₁c), insulin, homeostasis model assessment of insulin resistance (HOMA_IR), homeostasis model assessment-β-cell insulin secretion index (HOMA_IS), free fatty acid (FFA), total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride, and FAT% (the percentage of fat in vivo), 2-hinsulin (2hIns).

Table III.  Association of plasma preptin with IGT and T2DM in fully adjusted models. Results of multivariate logistic regression analysis are presented as the odds ratio (OR) in type 2 diabetes mellitus (T2DM), and impaired glucose tolerance (IGT) status decrease in plasma preptin.

	IGT			T2DM
Model adjusted	OR	95% CI	P	OR	95% CI	P
Plasma preptin
Age	1.004	0.999–1.009	0.082	1.007	1.003–1.012	0.002
Age, BP	1.004	0.999–1.009	0.085	1.008	1.003–1.013	0.001
Age, BP, BMI, WHR	1.005	1.000–1.010	0.069	1.009	1.004–1.015	0.000
Age, BP, BMI, WHR, FAT%	1.005	1.000–1.010	0.066	1.011	1.005–1.016	0.000
Age, BP, BMI, WHR, FAT%, lipid profile	1.004	0.998–1.009	0.195	1.009	1.003–1.015	0.003

BMI = body mass index; WHR = waist-to-hip; BP = blood pressure; FAT% = the percentage of fat in vivo; lipid profile = including total cholesterol, triglyceride, low- and high-density lipoprotein cholesterol; NGT = normal glucose tolerance;IGT = impaired glucose tolerance;DM = diabetes mellitus

Table IV.  Row mean scores differ and Cochran-Armitage trend analysis of the impact of plasma preptin level on type 2 diabetes mellitus. Values shown are cut-offs of plasma preptin levels of all subjects. Adjusted for age, sex, body mass index, waist-to-hip ratio, systolic blood pressure, diastolic blood pressure, total cholesterol, triglyceride, and low- and high-density lipoprotein cholesterol.

	Quartiles of preptin
Factor	Q1	Q2	Q3	Q4	Chi-square	P
Cut-off preptin (ng/L)	<350	350–450	450–550	≥550	9.4178^a	0.0021^a
No. of NGT/IGT/DM	19/16/3	21/21/29	14/15/9	0/4/9	3.0785^b	0.0021^b

^a Row mean scores differ test.

^b Cochran-Armitage trend test.; NGT = normal glucose tolerance; IGT = impaired glucose tolerance; DM = diabetes mellitus.