J Endocrinol Metab

Journal of Endocrinology and Metabolism, ISSN 1923-2861 print, 1923-287X online, Open Access

Article copyright, the authors; Journal compilation copyright, J Endocrinol Metab and Elmer Press Inc

Journal website https://www.jofem.org

Original Article

Volume 12, Number 1, February 2022, pages 19-31

Implication of Leptin and Leptin Receptor Gene Variations in Type 2 Diabetes Mellitus: A Case-Control Study

Figure 1. (a) Representative picture showing 451 bp PCR amplification product of 5′ end of the promoter region of LEP gene. (b) PCR-RFLP pattern of LEP G2548A polymorphism. L2, L3 and L4 represent homozygous variant genotype (AA; 451 bp); L5 represents homozygous wild genotype (GG; 402 and 49 bp); L1 and L6 represent heterozygous genotype (GA; 451, 402 and 49 bp); M: 100 bp molecular marker. PCR: polymerase chain reaction; LEP: leptin; RFLP: restriction fragment length polymorphism.

Figure 2. (a) Representative picture showing 212 bp PCR amplification product of exon 6 in LEPR gene. (b) PCR-RFLP pattern of LEPR Q223R polymorphism. L3, L5, L6 and L7 represent homozygous wild genotype (AA; 212 bp); L2 represents homozygous variant genotype (GG; 151 and 61 bp); L1 and L4 represent heterozygous genotype (GA; 221, 151 and 61 bp); M: 50 bp molecular marker. PCR: polymerase chain reaction; LEPR: leptin receptor; RFLP: restriction fragment length polymorphism.

**Table 1.** Demographic and Biochemical Characteristics of T2DM Cases and Controls Included in the Study
Characteristics	Controls (n = 408)	Cases (n = 390)	χ²	P value
*Statistically significant. T2DM: type 2 diabetes mellitus; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.
Age group					0.001	1.0
< 50 years	216	52.9	206	52.8
≥ 50 years	192	47.1	184	47.1
Gender					0.158	0.72
Male	168	41.2	166	42.5
Female	240	58.8	224	57.4
Dwelling					8.869	0.003*
Rural	144	35.3	178	45.6
Urban	264	64.7	212	54.3
Family history					27.962	< 0.0001*
No	216	52.9	134	34.3
Yes	192	47.1	256	65.6
BMI (kg/m²)					15.227	0.004*
Normal	120	29.4	118	30.3
Underweight	24	5.9	14	3.6
Preobese	120	29.4	148	37.9
Obese class I	120	29.4	78	20
Obese class II	24	5.9	32	8.2
Hypertension					22.107	0.0001*
No	264	64.7	188	48.2
Yes	144	35.3	202	51.8
Total cholesterol					23.227	< 0.0001*
Normal	264	64.7	312	80
Elevated	144	35.3	78	20
TG					0.479	0.523
Normal	216	52.9	216	55.4
Elevated	192	47.1	174	44.6
LDL-C					8.411	0.004*
Normal	312	76.5	330	84.6
Elevated	96	23.5	60	15.4
HDL-C					0.220	0.671
Normal	192	47	190	48.7
Low	216	53	200	51.3
HbA1c					434.917	< 0.0001*
Normal	384	94.1	84	21.5
High glycemic control	24	5.9	238	61
Low glycemic control	00	0	68	17.4
Insulin levels					30.568	< 0.0001*
Normal	264	64.7	320	82.1
Low	144	35.3	70	17.9
HOMA-IR					345.549	< 0.0001*
Insulin sensitive	360	88.2	110	28.2
Low IR	48	11.8	72	18.5
Significant IR	00	0.0	208	53.3
Leptin levels					188.638	< 0.0001*
Normal	360	88.2	164	42.1
Elevated	48	11.8	226	57.9

Table 1. Demographic and Biochemical Characteristics of T2DM Cases and Controls Included in the Study

Characteristics

Controls (n = 408)

Cases (n = 390)

χ²

P value

*Statistically significant. T2DM: type 2 diabetes mellitus; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.

Age group

0.001

1.0

< 50 years

216

52.9

206

52.8

≥ 50 years

192

47.1

184

47.1

Gender

0.158

0.72

Male

168

41.2

166

42.5

Female

240

58.8

224

57.4

Dwelling

8.869

0.003*

Rural

144

35.3

178

45.6

Urban

264

64.7

212

54.3

Family history

27.962

< 0.0001*

216

52.9

134

34.3

Yes

192

47.1

256

65.6

BMI (kg/m²)

15.227

0.004*

Normal

120

29.4

118

30.3

Underweight

5.9

3.6

Preobese

120

29.4

148

37.9

Obese class I

120

29.4

Obese class II

5.9

8.2

Hypertension

22.107

0.0001*

264

64.7

188

48.2

Yes

144

35.3

202

51.8

Total cholesterol

23.227

< 0.0001*

Normal

264

64.7

312

Elevated

144

35.3

0.479

0.523

Normal

216

52.9

216

55.4

Elevated

192

47.1

174

44.6

LDL-C

8.411

0.004*

Normal

312

76.5

330

84.6

Elevated

23.5

15.4

HDL-C

0.220

0.671

Normal

192

190

48.7

Low

216

200

51.3

HbA1c

434.917

< 0.0001*

Normal

384

94.1

21.5

High glycemic control

5.9

238

Low glycemic control

17.4

Insulin levels

30.568

< 0.0001*

Normal

264

64.7

320

82.1

Low

144

35.3

17.9

HOMA-IR

345.549

< 0.0001*

Insulin sensitive

360

88.2

110

28.2

Low IR

11.8

18.5

Significant IR

0.0

208

53.3

Leptin levels

188.638

< 0.0001*

Normal

360

88.2

164

42.1

Elevated

11.8

226

57.9

**Table 2.** Levels of Various Biochemical Parameters of T2DM Cases and Controls
Parameters	Controls, mean ± SD	Cases, mean ± SD	P value
*Statistically significant. T2DM: type 2 diabetes mellitus; HbA1c: glycosylated hemoglobin; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HOMA-IR: homeostatic model assessment-insulin resistance.
Age (years)	46.94 ± 6.81	47.39 ± 12.61	0.530
Fasting blood sugar (mg/dL)	90 ± 6.44	138.9 ± 73.26	< 0.0001*
HbA1c (%)	5.64 ± 0.33	7.68 ± 1.68	< 0.0001*
BMI (kg/m²)	26.82 ± 5.05	27.34 ± 5.05	0.0143*
Total cholesterol (mg/dL)	171 ± 51.57	165.27 ± 43.11	0.090
TG (mg/dL)	228.24 ± 229.03	160.82 ± 76.76	< 0.0001*
HDL-C (mg/dL)	43.76 ± 13.63	43.11 ± 13.87	0.504
LDL-C (mg/dL)	96.94 ± 38.58	93.46 ± 37.08	0.195
Insulin levels (µIU/mL)	6.27 ± 1.92	15.84 ± 16.86	< 0.0001*
HOMA-IR	1.4 ± 0.4	5.3 ± 5.9	< 0.0001*
Leptin levels (ng/mL)	7.22 ± 3.80	13.89 ± 9.21	< 0.0001*

Table 2. Levels of Various Biochemical Parameters of T2DM Cases and Controls

Parameters

Controls, mean ± SD

Cases, mean ± SD

P value

*Statistically significant. T2DM: type 2 diabetes mellitus; HbA1c: glycosylated hemoglobin; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HOMA-IR: homeostatic model assessment-insulin resistance.

Age (years)

46.94 ± 6.81

47.39 ± 12.61

0.530

Fasting blood sugar (mg/dL)

90 ± 6.44

138.9 ± 73.26

< 0.0001*

HbA1c (%)

5.64 ± 0.33

7.68 ± 1.68

< 0.0001*

BMI (kg/m²)

26.82 ± 5.05

27.34 ± 5.05

0.0143*

Total cholesterol (mg/dL)

171 ± 51.57

165.27 ± 43.11

0.090

TG (mg/dL)

228.24 ± 229.03

160.82 ± 76.76

< 0.0001*

HDL-C (mg/dL)

43.76 ± 13.63

43.11 ± 13.87

0.504

LDL-C (mg/dL)

96.94 ± 38.58

93.46 ± 37.08

0.195

Insulin levels (µIU/mL)

6.27 ± 1.92

15.84 ± 16.86

< 0.0001*

HOMA-IR

1.4 ± 0.4

5.3 ± 5.9

< 0.0001*

Leptin levels (ng/mL)

7.22 ± 3.80

13.89 ± 9.21

< 0.0001*

**Table 3.** Association Between Genotypic and Allelic Frequencies of the Leptin and Leptin Receptor Polymorphisms in T2DM Cases and Controls
Genotype/allele	Controls, n = 408 (%)	Cases, n = 390 (%)	Model 1	Model 2	Model 3
*Statistically significant. Model 1: unadjusted odds ratio and P value. Model 2: odds ratio and P value adjusted for age and gender using a multivariable logistic model. Model 3: odds ratio and P value adjusted for age, gender, dwelling, family history and other polymorphisms using a multivariable logistic model. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval.
LEP (rs7799039; G2548A)
Genotype
GG	288 (70.6)	118 (30.2)	Ref. (1.00)		Ref. (1.00)		Ref. (1.00)
GA	96 (23.5)	72 (18.5)	1.83 (1.2 - 2.6)	0.001*	2.0 (1.3 - 2.9)	< 0.0001*	1.1 (0.7 - 1.8)	0.4
AA	24 (5.9)	200 (51.3)	20.3 (12.6 - 32.6)	< 0.0001*	22.5 (13.8 - 36.5)	< 0.0001*	18.6 (10.6 - 32.4)	< 0.0001*
GA + AA	120 (29.4)	272 (69.8)	5.5 (4.0 - 7.4)	< 0.0001*	6.1 (4.5 - 8.4)	< 0.0001*	3.8 (2.7 - 5.6)	< 0.0001*
Allele type
G	672 (82.3)	308 (39.5)	Ref. (1.00)		Ref. (1.00)		Ref. (1.00)
A	144 (17.7)	472 (60.5)	7.1 (5.6 - 9.0)	< 0.0001*	7.7 (5.8 - 10.3)	< 0.0001*	5.9 (4.1 - 7.9)	< 0.0001*
LEPR (rs1137101; A668G; Q223R)
Genotype
AA	312 (76.4)	120 (30.8)	Ref. (1.00)		Ref. (1.00)		Ref. (1.00)
AG	48 (11.8)	110 (28.2)	5.9 (4.0 - 8.8)	< 0.0001*	6.6 (4.3 - 10.1)	< 0.0001*	6.5 (4.0 - 10.6)	< 0.0001*
GG	48 (11.8)	160 (41.0)	8.6 (5.9 - 12.7)	< 0.0001*	9.5 (6.4 - 14.1)	< 0.0001*	7.6 (4.6 - 12.5)	< 0.0001*
AG + GG	96 (23.6)	270 (69.2)	7.3 (5.3 - 10.0)	< 0.0001*	8.1 (5.1 - 11.2)	< 0.0001*	7.3 (4.9 - 10.7)	< 0.0001*
Allele type
A	672 (82.3)	350 (44.8)	Ref. (1.00)		Ref. (1.00)		Ref. (1.00)
G	144 (17.7)	430 (55.2)	5.7 (4.5 - 7.2)	< 0.0001*	6.5 (4.9 - 9.5)	< 0.0001*	4.8 (3.6 - 6.5)	< 0.0001*

Table 3. Association Between Genotypic and Allelic Frequencies of the Leptin and Leptin Receptor Polymorphisms in T2DM Cases and Controls

Genotype/allele

Controls, n = 408 (%)

Cases, n = 390 (%)

Model 1

Model 2

Model 3

OR (95% CI)

P value

OR (95% CI)

P value

OR (95% CI)

P value

*Statistically significant. Model 1: unadjusted odds ratio and P value. Model 2: odds ratio and P value adjusted for age and gender using a multivariable logistic model. Model 3: odds ratio and P value adjusted for age, gender, dwelling, family history and other polymorphisms using a multivariable logistic model. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval.

LEP (rs7799039; G2548A)

Genotype

288 (70.6)

118 (30.2)

Ref. (1.00)

96 (23.5)

72 (18.5)

1.83 (1.2 - 2.6)

0.001*

2.0 (1.3 - 2.9)

< 0.0001*

1.1 (0.7 - 1.8)

0.4

24 (5.9)

200 (51.3)

20.3 (12.6 - 32.6)

< 0.0001*

22.5 (13.8 - 36.5)

< 0.0001*

18.6 (10.6 - 32.4)

< 0.0001*

GA + AA

120 (29.4)

272 (69.8)

5.5 (4.0 - 7.4)

< 0.0001*

6.1 (4.5 - 8.4)

< 0.0001*

3.8 (2.7 - 5.6)

< 0.0001*

Allele type

672 (82.3)

308 (39.5)

Ref. (1.00)

144 (17.7)

472 (60.5)

7.1 (5.6 - 9.0)

< 0.0001*

7.7 (5.8 - 10.3)

< 0.0001*

5.9 (4.1 - 7.9)

< 0.0001*

LEPR (rs1137101; A668G; Q223R)

Genotype

312 (76.4)

120 (30.8)

Ref. (1.00)

48 (11.8)

110 (28.2)

5.9 (4.0 - 8.8)

< 0.0001*

6.6 (4.3 - 10.1)

< 0.0001*

6.5 (4.0 - 10.6)

< 0.0001*

48 (11.8)

160 (41.0)

8.6 (5.9 - 12.7)

< 0.0001*

9.5 (6.4 - 14.1)

< 0.0001*

7.6 (4.6 - 12.5)

< 0.0001*

AG + GG

96 (23.6)

270 (69.2)

7.3 (5.3 - 10.0)

< 0.0001*

8.1 (5.1 - 11.2)

< 0.0001*

7.3 (4.9 - 10.7)

< 0.0001*

Allele type

672 (82.3)

350 (44.8)

Ref. (1.00)

144 (17.7)

430 (55.2)

5.7 (4.5 - 7.2)

< 0.0001*

6.5 (4.9 - 9.5)

< 0.0001*

4.8 (3.6 - 6.5)

< 0.0001*

**Table 4.** Association Between *LEP G2548A* Genotypes and Various Socio-Demographic and Clinicopathological Characteristics of T2DM Cases and Controls
Socio-demographic/clinicopathological parameters	LEP G2548A genotypes in controls	LEP G2548A genotypes in T2DM cases	OR (95% CI)	P value
*Statistically significant. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval; BMI: body mass index (< 18.5: underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.
Age group
< 50 years	216 (52.9)	144 (66.7)	72 (33.3)	206 (52.8)	70 (34.0)	136 (66.0)	3.88 (2.5 - 5.8)	< 0.0001*
≥ 50 years	192 (47.1)	144 (75.0)	48 (25.0)	184 (47.1)	48 (26.1)	136 (73.9)	8.5 (5.3 - 13.5)	< 0.0001*
Gender
Male	168 (41.2)	144 (85.7)	24 (14.3)	166 (42.5)	62 (37.3)	104 (62.7)	10.0 (5.8 - 17.1)	< 0.0001*
Female	240 (58.8)	144 (60.0)	96 (40.0)	224 (57.4)	56 (25.0)	168 (75.0)	4.5 (3.0 - 6.6)	< 0.0001*
Dwelling
Rural	144 (35.3)	120 (83.3)	24 (16.7)	178 (45.6)	56 (31.5)	122 (68.5)	10.8 (6.3 - 18.7)	< 0.0001*
Urban	264 (64.7)	168 (63.6)	96 (36.4)	212 (54.3)	62 (29.2)	96 (36.4)	4.2 (2.8 - 6.2)	< 0.0001*
Family history
No	216 (52.9)	192 (88.9)	24 (11.1)	134 (34.3)	34 (25.4)	100 (74.6)	23.5 (13.2 - 41.8)	< 0.0001*
Yes	192 (47.1)	96 (50.0)	96 (50.0)	256 (65.6)	84 (32.8)	172 (67.2)	2.0 (1.3 - 3.0)	< 0.0001*
BMI (kg/m²)
Normal	120 (29.4)	96 (80.0)	24 (20)	118 (30.3)	36 (30.5)	82 (69.5)	9.1 (5.0 - 16.5)	< 0.0001*
Underweight	24 (5.9)	24 (100)	0 (0.0)	14 (3.6)	02 (14.3)	12 (85.7)	-	< 0.0001*
Preobese	120 (29.4)	120 (100)	0 (0.0)	148 (37.9)	46 (31.1)	102 (68.9)	-	< 0.0001*
Obese class I	120 (29.4)	48 (40.0)	72 (60)	78 (20.0)	22 (28.2)	56 (71.8)	1.6 (0.9 - 3.1)	0.061
Obese class II	24 (5.9)	0 (0.0)	24 (100)	32 (8.2)	12 (37.5)	20 (62.5)	-	< 0.0001*
Hypertension
No	264 (64.7)	240 (90.9)	24 (9.1)	188 (48.2)	58 (30.9)	130 (69.1)	22.4 (13.3 - 37.7)	< 0.0001*
Yes	144 (35.3)	48 (33.3)	96 (66.7)	202 (51.8)	60 (29.7)	142 (70.3)	1.1 (0.7 - 1.8)	0.482
Total cholesterol
Normal	264 (64.7)	168 (63.6)	96 (36.4)	312 (80.0)	92 (29.5)	220 (70.5)	4.1 (2.9 - 5.9)	< 0.0001*
Elevated	144 (35.3)	120 (83.3)	24 (16.7)	78 (20.0)	26 (33.3)	52 (66.7)	10.0 (5.2 - 19.0)	< 0.0001*
TG
Normal	216 (52.9)	168 (77.8)	48 (22.2)	216 (55.4)	54 (25.0)	162 (75)	10.5 (6.7 - 16.3)	< 0.0001*
Elevated	192 (47.1)	120 (62.5)	72 (37.5)	174 (44.6)	64 (36.8)	110 (63.2)	2.8 (1.8 - 4.3)	< 0.0001*
LDL-C
Normal	312 (76.5)	216 (69.2)	96 (30.8)	330 (84.6)	102 (30.9)	228 (69.1)	5.02 (3.5 - 7.0)	< 0.0001*
Elevated	96 (23.5)	72 (75.0)	24 (25.0)	60 (15.4)	16 (26.7)	44 (73.3)	8.2 (3.9 - 17.2)	< 0.0001*
HDL-C
Normal	192 (47.0)	144 (75.0)	48 (25.0)	190 (48.7)	54 (28.4)	136 (71.6)	7.55 (4.7 - 11.8)	< 0.0001*
Low	216 (53.0)	144 (66.7)	72 (33.3)	200 (51.3)	64 (32.0)	136 (68.0)	4.2 (2.8 - 6.4)	< 0.0001*
HbA1c
Normal	384 (94.1)	264 (68.7)	120 (31.3)	84 (21.5)	18 (21.4)	66 (78.6)	8.0 (4.5 - 14.1)	< 0.0001*
High glycemic control	24 (5.9)	24 (100)	0 (0.0)	238 (61.0)	82 (34.5)	156 (65.5)	-	< 0.0001*
Low glycemic control	0 (0.0)	0 (0.0)	0 (0 .0)	68 (17.4)	18 (26.5)	50 (73.5)	-	< 0.0001*
Insulin levels
Normal	264 (64.7)	168 (63.6)	96 (36.4)	320 (82.1)	98 (30.6)	222 (69.4)	3.96 (2.8 - 5.6)	< 0.0001*
Low	144 (35.3)	120 (83.3)	24 (16.7)	70 (17.9)	20 (28.6)	50 (71.4)	12.5 (6.3 - 24.6)	< 0.0001*
HOMA-IR
Insulin sensitive	360 (88.2)	240 (66.7)	120 (33.3)	110 (28.2)	34 (30.9)	76 (69.1)	4.4 (2.8 - 7.0)	< 0.0001*
Low IR	48 (11.8)	48 (100)	0 (0.0)	72 (18.5)	18 (25.0)	54 (75.0)	-	< 0.0001*
Significant IR	0 (0.0)	0 (0.0)	0 (0.0)	208 (53.3)	66 (31.7)	142 (68.3)	-	< 0.0001*
Leptin levels
Normal	360 (88.2)	264 (73.3)	96 (26.7)	164 (42.1)	38 (23.2)	126 (76.8)	9.1 (5.9 - 14.0)	< 0.0001*
Elevated	48 (11.8)	24 (50.0)	24 (50.0)	226 (57.9)	80 (35.4)	146 (64.6)	1.8 (0.97 - 3.4)	0.072

Table 4. Association Between LEP G2548A Genotypes and Various Socio-Demographic and Clinicopathological Characteristics of T2DM Cases and Controls

Socio-demographic/clinicopathological parameters

LEP G2548A genotypes in controls

LEP G2548A genotypes in T2DM cases

OR (95% CI)

P value

n = 408 (%)

GG, 288 (70.6)

GA + AA, 120 (29.4)

n = 390 (%)

GG, 118 (30.2)

GA + AA, 272 (69.8)

5.5 (4.0 - 7.4)

< 0.0001*

*Statistically significant. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval; BMI: body mass index (< 18.5: underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.

Age group

< 50 years

216 (52.9)

144 (66.7)

72 (33.3)

206 (52.8)

70 (34.0)

136 (66.0)

3.88 (2.5 - 5.8)

< 0.0001*

≥ 50 years

192 (47.1)

144 (75.0)

48 (25.0)

184 (47.1)

48 (26.1)

136 (73.9)

8.5 (5.3 - 13.5)

< 0.0001*

Gender

Male

168 (41.2)

144 (85.7)

24 (14.3)

166 (42.5)

62 (37.3)

104 (62.7)

10.0 (5.8 - 17.1)

< 0.0001*

Female

240 (58.8)

144 (60.0)

96 (40.0)

224 (57.4)

56 (25.0)

168 (75.0)

4.5 (3.0 - 6.6)

< 0.0001*

Dwelling

Rural

144 (35.3)

120 (83.3)

24 (16.7)

178 (45.6)

56 (31.5)

122 (68.5)

10.8 (6.3 - 18.7)

< 0.0001*

Urban

264 (64.7)

168 (63.6)

96 (36.4)

212 (54.3)

62 (29.2)

96 (36.4)

4.2 (2.8 - 6.2)

< 0.0001*

Family history

216 (52.9)

192 (88.9)

24 (11.1)

134 (34.3)

34 (25.4)

100 (74.6)

23.5 (13.2 - 41.8)

< 0.0001*

Yes

192 (47.1)

96 (50.0)

256 (65.6)

84 (32.8)

172 (67.2)

2.0 (1.3 - 3.0)

< 0.0001*

BMI (kg/m²)

Normal

120 (29.4)

96 (80.0)

24 (20)

118 (30.3)

36 (30.5)

82 (69.5)

9.1 (5.0 - 16.5)

< 0.0001*

Underweight

24 (5.9)

24 (100)

0 (0.0)

14 (3.6)

02 (14.3)

12 (85.7)

< 0.0001*

Preobese

120 (29.4)

120 (100)

0 (0.0)

148 (37.9)

46 (31.1)

102 (68.9)

< 0.0001*

Obese class I

120 (29.4)

48 (40.0)

72 (60)

78 (20.0)

22 (28.2)

56 (71.8)

1.6 (0.9 - 3.1)

0.061

Obese class II

24 (5.9)

0 (0.0)

24 (100)

32 (8.2)

12 (37.5)

20 (62.5)

< 0.0001*

Hypertension

264 (64.7)

240 (90.9)

24 (9.1)

188 (48.2)

58 (30.9)

130 (69.1)

22.4 (13.3 - 37.7)

< 0.0001*

Yes

144 (35.3)

48 (33.3)

96 (66.7)

202 (51.8)

60 (29.7)

142 (70.3)

1.1 (0.7 - 1.8)

0.482

Total cholesterol

Normal

264 (64.7)

168 (63.6)

96 (36.4)

312 (80.0)

92 (29.5)

220 (70.5)

4.1 (2.9 - 5.9)

< 0.0001*

Elevated

144 (35.3)

120 (83.3)

24 (16.7)

78 (20.0)

26 (33.3)

52 (66.7)

10.0 (5.2 - 19.0)

< 0.0001*

Normal

216 (52.9)

168 (77.8)

48 (22.2)

216 (55.4)

54 (25.0)

162 (75)

10.5 (6.7 - 16.3)

< 0.0001*

Elevated

192 (47.1)

120 (62.5)

72 (37.5)

174 (44.6)

64 (36.8)

110 (63.2)

2.8 (1.8 - 4.3)

< 0.0001*

LDL-C

Normal

312 (76.5)

216 (69.2)

96 (30.8)

330 (84.6)

102 (30.9)

228 (69.1)

5.02 (3.5 - 7.0)

< 0.0001*

Elevated

96 (23.5)

72 (75.0)

24 (25.0)

60 (15.4)

16 (26.7)

44 (73.3)

8.2 (3.9 - 17.2)

< 0.0001*

HDL-C

Normal

192 (47.0)

144 (75.0)

48 (25.0)

190 (48.7)

54 (28.4)

136 (71.6)

7.55 (4.7 - 11.8)

< 0.0001*

Low

216 (53.0)

144 (66.7)

72 (33.3)

200 (51.3)

64 (32.0)

136 (68.0)

4.2 (2.8 - 6.4)

< 0.0001*

HbA1c

Normal

384 (94.1)

264 (68.7)

120 (31.3)

84 (21.5)

18 (21.4)

66 (78.6)

8.0 (4.5 - 14.1)

< 0.0001*

High glycemic control

24 (5.9)

24 (100)

0 (0.0)

238 (61.0)

82 (34.5)

156 (65.5)

< 0.0001*

Low glycemic control

0 (0.0)

0 (0 .0)

68 (17.4)

18 (26.5)

50 (73.5)

< 0.0001*

Insulin levels

Normal

264 (64.7)

168 (63.6)

96 (36.4)

320 (82.1)

98 (30.6)

222 (69.4)

3.96 (2.8 - 5.6)

< 0.0001*

Low

144 (35.3)

120 (83.3)

24 (16.7)

70 (17.9)

20 (28.6)

50 (71.4)

12.5 (6.3 - 24.6)

< 0.0001*

HOMA-IR

Insulin sensitive

360 (88.2)

240 (66.7)

120 (33.3)

110 (28.2)

34 (30.9)

76 (69.1)

4.4 (2.8 - 7.0)

< 0.0001*

Low IR

48 (11.8)

48 (100)

0 (0.0)

72 (18.5)

18 (25.0)

54 (75.0)

< 0.0001*

Significant IR

0 (0.0)

208 (53.3)

66 (31.7)

142 (68.3)

< 0.0001*

Leptin levels

Normal

360 (88.2)

264 (73.3)

96 (26.7)

164 (42.1)

38 (23.2)

126 (76.8)

9.1 (5.9 - 14.0)

< 0.0001*

Elevated

48 (11.8)

24 (50.0)

226 (57.9)

80 (35.4)

146 (64.6)

1.8 (0.97 - 3.4)

0.072

**Table 5.** Association Between *LEPR A668G (Q223R)* Genotypes and Various Socio-Demographic and Clinicopathological Characteristics of T2DM Cases and Controls
Socio-demographic/clinicopathological parameters	LEPR A668G genotypes in controls	LEPR A668G genotypes in T2DM cases	OR (95% CI)	P value
*Statistically significant. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.
Age group
< 50 years	216 (52.9)	192 (88.9)	24 (11.1)	206 (52.8)	64 (31.1)	142 (98.9)	17.7 (10.5 - 29.7)	< 0.0001*
≥ 50 years	192 (47.1)	120 (62.5)	72 (37.5)	184 (47.1)	56 (30.4)	128 (69.6)	3.8 (2.4 - 5.8)	< 0.0001*
Gender
Male	168 (41.2)	96 (57.1)	72 (42.9)	166 (42.5)	54 (32.5)	112 (67.5)	2.7 (17 - 4.3)	< 0.0001*
Female	240 (58.8)	216 (90.0)	24 (10.0)	224 (57.4)	66 (29.5)	158 (70.5)	21.5 (12.9 - 35.8)	< 0.0001*
Dwelling
Rural	144 (35.3)	144 (100)	0 (0.0)	178 (45.6)	60 (33.7)	118 (66.3)	-	< 0.0001*
Urban	264 (64.7)	168 (63.6)	96 (36.4)	212 (54.3)	60 (28.3)	152 (71.7)	4.43 (3.0 - 6.5)	< 0.0001*
Family history
No	216 (52.9)	192 (88.9)	24 (11.1)	134 (34.3)	40 (29.9)	94 (70.1)	18.8 (10.7 - 33)	< 0.0001*
Yes	192 (47.1)	120 (62.5)	72 (37.5)	256 (65.6)	80 (31.3)	176 (68.8)	3.6 (2.4 - 5.4)	< 0.0001*
BMI (kg/m²)
Normal	120 (29.4)	120 (100)	0 (0.0)	118 (30.3)	44 (37.3)	74 (62.7)	-	< 0.0001*
Underweight	24 (5.9)	24 (100)	0 (0.0)	14 (3.6)	4 (28.6)	10 (71.4)	-	< 0.0001*
Preobese	120 (29.4)	72 (60.0)	48 (40.0)	148 (37.9)	40 (27.0)	108 (73.0)	4.0 (2.4 - 6.7)	< 0.0001*
Obese class I	120 (29.4)	96 (80.0)	24 (20.0)	78 (20.0)	22 (28.2)	56 (71.8)	10.1 (5.2 - 19.8)	< 0.0001*
Obese class II	24 (5.9)	0 (0.0)	24 (100)	32 (8.2)	10 (31.3)	22 (68.8)	-	0.002*
Hypertension
No	264 (64.7)	216 (81.8)	48 (18.2)	188 (48.2)	70 (37.2)	118 (62.8)	7.5 (4.9 - 11.6)	< 0.0001*
Yes	144 (35.3)	96 (66.7)	48 (33.3)	202 (51.8)	50 (24.8)	152 (75.2)	6.0 (3.7 - 9.7)	< 0.0001*
Total cholesterol
Normal	264 (64.7)	216 (81.8)	48 (18.2)	312 (80.0)	94 (30.1)	218 (69.9)	10.4 (7.0 - 15.4)	< 0.0001*
Elevated	144 (35.3)	96 (66.7)	48 (33.3)	78 (20.0)	26 (33.3)	52 (66.7)	4.0 (2.2 - 7.1)	< 0.0001*
TG
Normal	216 (52.9)	192 (88.9)	24 (11.1)	216 (55.4)	64 (29.6)	152 (70.4)	19.0 (11.3 - 31.8)	< 0.0001*
Elevated	192 (47.1)	120 (62.5)	72 (37.5)	174 (44.6)	56 (32.2)	118 (67.8)	3.5 (2.2 - 5.4)	< 0.0001*
LDL-C
Normal	312 (76.5)	264 (84.6)	48 (15.4)	330 (84.6)	100 (30.3)	230 (69.7)	12.6 (8.5 - 18.6)	< 0.0001*
Elevated	96 (23.5)	48 (50.0)	48 (50.0)	60 (15.4)	20 (33.3)	40 (66.7)	2.0 (1.0 - 3.9)	0.047*
HDL-C
Normal	192 (47.0)	168 (87.5)	24 (12.5)	190 (48.7)	58 (30.5)	132 (69.5)	15.9 (9.4 - 26.9)	< 0.0001*
Low	216 (53.0)	144 (66.7)	72 (33.3)	200 (51.3)	62 (31.0)	138 (69.0)	2.8 (2.2 - 3.5)	< 0.0001*
HbA1c
Normal	384 (94.1)	288 (75.0)	96 (25.0)	84 (21.5)	26 (31.0)	58 (69.0)	6.6 (3.9 - 11.2)	< 0.0001*
High glycemic control	24 (5.9)	24 (100)	0 (0.0)	238 (61.0)	72 (30.3)	166 (63.4)	-	< 0.0001*
Low glycemic control	0 (0.0)	0 (0.0)	0 (0.0)	68 (17.4)	22 (32.4)	46 (67.6)	-	< 0.0001*
Insulin levels
Normal	264 (64.7)	192 (72.7)	72 (27.3)	320 (82.1)	96 (30.0)	224 (70.0)	6.2 (4.3 - 8.9)	< 0.0001*
Low	144 (35.3)	120 (83.3)	24 (16.7)	70 (17.9)	24 (34.3)	46 (65.7)	9.5 (4.9 - 18.5)	< 0.0001*
HOMA-IR
Insulin sensitive	360 (88.2)	288 (80.0)	72 (20.0)	110 (28.2)	34 (30.9)	76 (69.1)	8.9 (5.5 - 14.4)	< 0.0001*
Low IR	48 (11.8)	24 (50.0)	24 (50.0)	72 (18.5)	22 (30.6)	50 (69.4)	2.2 (1.0 - 4.8)	0.037*
Significant IR	0 (0.0)	0 (0.0)	0 (0.0)	208 (53.3)	64 (30.8)	114 (69.2)	-	< 0.0001*
Leptin levels
Normal	360 (88.2)	288 (80)	72 (20.0)	164 (42.1)	62 (37.8)	102 (62.2)	6.5 (4.3 - 9.8)	< 0.0001*
Elevated	48 (11.8)	24 (50.0)	24 (50.0)	226 (57.9)	58 (25.7)	168 (74.3)	2.8 (1.5 - 5.4)	0.02*

Table 5. Association Between LEPR A668G (Q223R) Genotypes and Various Socio-Demographic and Clinicopathological Characteristics of T2DM Cases and Controls

Socio-demographic/clinicopathological parameters

LEPR A668G genotypes in controls

LEPR A668G genotypes in T2DM cases

OR (95% CI)

P value

n = 408 (%)

AA, 312 (46.6)

AG + GG, 96 (53.3)

n = 390 (%)

AA, 120 (30.7)

AG + GG, 270 (69.3)

7.3 (5.3 - 10.0)

< 0.0001*

*Statistically significant. T2DM: type 2 diabetes mellitus; OR: odds ratio; CI: confidence interval; BMI: body mass index (< 18.5 = underweight, 18.5 - 24.99 = normal, 25 - 29.99 = preobese, 30 - 34.99 = obese class I, 35 - 39.99 = obese class II); TG: triglycerides; LDL-C: low-density lipoprotein cholesterol; HDL-C: high-density lipoprotein cholesterol; HbA1c: glycosylated hemoglobin; HOMA-IR: homeostatic model assessment-insulin resistance.

Age group

< 50 years

216 (52.9)

192 (88.9)

24 (11.1)

206 (52.8)

64 (31.1)

142 (98.9)

17.7 (10.5 - 29.7)

< 0.0001*

≥ 50 years

192 (47.1)

120 (62.5)

72 (37.5)

184 (47.1)

56 (30.4)

128 (69.6)

3.8 (2.4 - 5.8)

< 0.0001*

Gender

Male

168 (41.2)

96 (57.1)

72 (42.9)

166 (42.5)

54 (32.5)

112 (67.5)

2.7 (17 - 4.3)

< 0.0001*

Female

240 (58.8)

216 (90.0)

24 (10.0)

224 (57.4)

66 (29.5)

158 (70.5)

21.5 (12.9 - 35.8)

< 0.0001*

Dwelling

Rural

144 (35.3)

144 (100)

0 (0.0)

178 (45.6)

60 (33.7)

118 (66.3)

< 0.0001*

Urban

264 (64.7)

168 (63.6)

96 (36.4)

212 (54.3)

60 (28.3)

152 (71.7)

4.43 (3.0 - 6.5)

< 0.0001*

Family history

216 (52.9)

192 (88.9)

24 (11.1)

134 (34.3)

40 (29.9)

94 (70.1)

18.8 (10.7 - 33)

< 0.0001*

Yes

192 (47.1)

120 (62.5)

72 (37.5)

256 (65.6)

80 (31.3)

176 (68.8)

3.6 (2.4 - 5.4)

< 0.0001*

BMI (kg/m²)

Normal

120 (29.4)

120 (100)

0 (0.0)

118 (30.3)

44 (37.3)

74 (62.7)

< 0.0001*

Underweight

24 (5.9)

24 (100)

0 (0.0)

14 (3.6)

4 (28.6)

10 (71.4)

< 0.0001*

Preobese

120 (29.4)

72 (60.0)

48 (40.0)

148 (37.9)

40 (27.0)

108 (73.0)

4.0 (2.4 - 6.7)

< 0.0001*

Obese class I

120 (29.4)

96 (80.0)

24 (20.0)

78 (20.0)

22 (28.2)

56 (71.8)

10.1 (5.2 - 19.8)

< 0.0001*

Obese class II

24 (5.9)

0 (0.0)

24 (100)

32 (8.2)

10 (31.3)

22 (68.8)

0.002*

Hypertension

264 (64.7)

216 (81.8)

48 (18.2)

188 (48.2)

70 (37.2)

118 (62.8)

7.5 (4.9 - 11.6)

< 0.0001*

Yes

144 (35.3)

96 (66.7)

48 (33.3)

202 (51.8)

50 (24.8)

152 (75.2)

6.0 (3.7 - 9.7)

< 0.0001*

Total cholesterol

Normal

264 (64.7)

216 (81.8)

48 (18.2)

312 (80.0)

94 (30.1)

218 (69.9)

10.4 (7.0 - 15.4)

< 0.0001*

Elevated

144 (35.3)

96 (66.7)

48 (33.3)

78 (20.0)

26 (33.3)

52 (66.7)

4.0 (2.2 - 7.1)

< 0.0001*

Normal

216 (52.9)

192 (88.9)

24 (11.1)

216 (55.4)

64 (29.6)

152 (70.4)

19.0 (11.3 - 31.8)

< 0.0001*

Elevated

192 (47.1)

120 (62.5)

72 (37.5)

174 (44.6)

56 (32.2)

118 (67.8)

3.5 (2.2 - 5.4)

< 0.0001*

LDL-C

Normal

312 (76.5)

264 (84.6)

48 (15.4)

330 (84.6)

100 (30.3)

230 (69.7)

12.6 (8.5 - 18.6)

< 0.0001*

Elevated

96 (23.5)

48 (50.0)

60 (15.4)

20 (33.3)

40 (66.7)

2.0 (1.0 - 3.9)

0.047*

HDL-C

Normal

192 (47.0)

168 (87.5)

24 (12.5)

190 (48.7)

58 (30.5)

132 (69.5)

15.9 (9.4 - 26.9)

< 0.0001*

Low

216 (53.0)

144 (66.7)

72 (33.3)

200 (51.3)

62 (31.0)

138 (69.0)

2.8 (2.2 - 3.5)

< 0.0001*

HbA1c

Normal

384 (94.1)

288 (75.0)

96 (25.0)

84 (21.5)

26 (31.0)

58 (69.0)

6.6 (3.9 - 11.2)

< 0.0001*

High glycemic control

24 (5.9)

24 (100)

0 (0.0)

238 (61.0)

72 (30.3)

166 (63.4)

< 0.0001*

Low glycemic control

0 (0.0)

68 (17.4)

22 (32.4)

46 (67.6)

< 0.0001*

Insulin levels

Normal

264 (64.7)

192 (72.7)

72 (27.3)

320 (82.1)

96 (30.0)

224 (70.0)

6.2 (4.3 - 8.9)

< 0.0001*

Low

144 (35.3)

120 (83.3)

24 (16.7)

70 (17.9)

24 (34.3)

46 (65.7)

9.5 (4.9 - 18.5)

< 0.0001*

HOMA-IR

Insulin sensitive

360 (88.2)

288 (80.0)

72 (20.0)

110 (28.2)

34 (30.9)

76 (69.1)

8.9 (5.5 - 14.4)

< 0.0001*

Low IR

48 (11.8)

24 (50.0)

72 (18.5)

22 (30.6)

50 (69.4)

2.2 (1.0 - 4.8)

0.037*

Significant IR

0 (0.0)

208 (53.3)

64 (30.8)

114 (69.2)

< 0.0001*

Leptin levels

Normal

360 (88.2)

288 (80)

72 (20.0)

164 (42.1)

62 (37.8)

102 (62.2)

6.5 (4.3 - 9.8)

< 0.0001*

Elevated

48 (11.8)

24 (50.0)

226 (57.9)

58 (25.7)

168 (74.3)

2.8 (1.5 - 5.4)

0.02*