INTRODUCTION:

Diabetes mellitus is collectively a metabolic disorder and is characterised by long term hyperglycemia due to defect in insulin secretion, insulin action or by both of them. An insulin is an anabolic hormone, its abnormalities affect metabolism of carbohydrate fat and proteins. American Diabetic Association purpose Diabetes to be classified into type 1 and type 2 mainly. Other types of diabetes and gestational diabetes are still accepted and adopted by ADA. [1] Among types of diabetes, diabetes type 2 is long term metabolic disorder; its occurrence has been increasing heavily world-wide. In 1988 DM was known as a component of metabolic syndrome. Type 2 DM was formerly known as Non-insulin Dependent DM, it is a common form of DM characterised by hyperglycemia, Insulin Resistance as well as improper insulin insufficiency. [2, 3]

Worldwide 193million people have undiagnosed diabetes and around 415 million people are living their life with diabetes. Among them, type 2diabetes accounts approximately 90% of cases, it develops micro vascular and macro vascular complications which causes psychological and physical distress and puts a huge burden on the health care system and providers. [4,5]

Leptin was discovered around 2 decades ago, it brought huge excitement for the treatment of obesity. Prototypical adipocyte secreted protein cytokine was named leptin. It was derived from greek word “leptos” for thin. It also pioneered the concept towards adipose tissue that it's not just an inert energy storage organ but an active endocrine organ. [6] Leptin is a product of 167 amino acids of the human leptin gene, it was first originally discovered through positional cloning of ob/ob mice, a mouse model at Jackson Laboratories. [7]

It is secreted generally in white adipose tissue, and its levels are positively correlated to levels of fat in the body. Leptin has hormonal type secretion as it is secreted in pulsatile fashion and has significant diurnal variation with elevated levels during evening and early morning hours. Leptin circulation in the body reflects the amount of energy stored in fat and acute changes in calorie intake. [8, 9]

In extremely rare caese of obese humans, deficiency of leptin has been described due to homozygous mutation of leptin gene. Generally obese persons have high circulating leptin levels and are either resistant or tolerant to is weight reducing effects.[6,10] Deficiency or resistance of leptin may cause uncontrolled intake of food, obesity and diabetes mellitus. It may also lead to atherosclerosis, Hypertension and CVD. Obesity has been emerging in the world's population [11, 12]. Prevalence of Type 2DM, CAD in urban and migrant Asians Indians is increased despite other traditional risk factors [13]. There is evidence that states Asian Indians are more hyperinsulinemic as compared to Caucasians, and most importantly hyperinsulinemia may have more vital role in development of these diseases. [3, 14]

Obese subjects generally persists high level of leptin which correlate with BMI and body fat percentage. Although correlation between BMI and leptin exists. In men, BMI was the variable which was most strongly correlated with leptin [15] while few studies observed no significant differences in between BMI and diabetes with leptin. [16]

Aim:

This study was aimed to analyse in depth the latent role of leptin in a mechanism underlying obesity and type 2 diabetes mellitus. To this end, suggestive markers of type 2 diabetes mellitus and obesity were estimated in blood samples and their associations with leptin were observed.

MATERIAL AND METHODS:

Study design:

The study was designed to be cross sectional observational study for the period of one year in tertiary care hospital in India. The study consisted of face to face questionnaire interviews, physical examinations, and laboratory analysis.

Subjects:

200 Subjects were enrolled in present studies among them 50 of them were males and rest of 50 were females. And 100 controls were also included

Selection of subjects:

100 subjects were taken with the following inclusion and exclusion criteria. And 100 age sex matched healthy subjects without diabetes and obesity were included.

Inclusion criteria:

· Subjects with in age group 20-70

· Subjects diagnosed with diabetes mellitus type 2

· Subjects Without obesity were included in study

Exclusion criteria:

· Unwilling participant

· Patients with known diagnosis of type-1 DM,

· hypothyroidism, chronic renal failure, nephrotic syndrome, familial hypercholesteraemic syndromes

· Liver disease, anaemia and patients already on lipid lowering drugs were excluded from the study.

Adiposity measures:

Anthropometric data were measured following standard protocols. Weight was measured with light cloth and no shoes. BMI was calculated as weight in (kg)/ height square in meters (m2). Patients were categorised into underweight (<18.5 kg/m2), normal (18.5-22.9 kg/m2), overweight (23-24.9 kg/m2) and obese if (>25 kg/m2) based on revised guidelines for India.[17] Waist circumference and central obesity was defined WC≥90 cm in men and ≥80 cm in women according to the International Diabetes Federation criteria [18]

Collection and processing of blood sample:

After overnight fasting five ml of venous blood was drawn from the subject and control after written and informed consent, in dry disposable syringe under aseptic conditions and was transferred to a sterile, dry and acid washed vial for biochemical analysis. Sample was allowed to clot at room temperature, centrifugation at 2500 -3000 rpm for 15 minutes and serum was then processed for estimation of total cholesterol by CHOD-PAP Enzymatic method.[19] Triglycerides TG by glycerol phosphate oxidase. (GPO)-tinder method.[19-21] HDL by precipitation method.[22] LDL and VLDL was calculated by Friedewalds equation. Fasting blood sugar by GOD-POD method [23,24]

Levels of serum leptin were estimated using RIA in venous blood samples (Linco Research Inc, St Charles, MO) [25] The data obtained was entered in a pre-tested study proforma and analysed. Diabetes mellitus was defined if fasting plasma glucose was >126 mg/dL or 2 hours postprandial >200 mg/dL or HbA1c >6.5 or patient was on anti-diabetic medicine. [26]

Statistical Analysis:

Data collected was entered into Microsoft Excel Worksheet and statistically analysed by using SPSS (Statistical Package for Social Sciences) version 20. For quantitative data mean, standard mean, standard deviation, t-test and Karl Pearson’s Coefficient of Correlation were calculated. P value < 0.05 (0.01) will be considered as statically significant (highly significant) at 95% confidence interval.

Ethical considerations:

Informed and written consent was taken from each subject before collecting data and blood samples. Only those individuals, who volunteered to participate in the study, were included and the data was kept confidential. The study did not impose any burden on the subjects and the Institute; therefore the study is ethically justified. The proposed study was undertaken subject to approval by the Institutional Ethical Committee.

RESULT AND OBSERVATION:

Table 1: Distribution of study groups under baseline characteristics: age, gender, BMI, Diabetes mellitus

Baseline characteristics of subjects	N(%)
Age in years:
20-40	20(20%)
40-60	64(64%)
>60	16(16%)
Mean Age	55.34± 2.43years
Gender:
Male	50(50%)
Female	50(50%)
Body mass index:
18.5-25	16(16%)
25-30	28(28%)
>30	56(56%)
Mean BMI	32.19±3.22

Above table depicts 64% of subjects were between the age group of 40-60 and mean age was 55.34 ± 2.43years. 56% of the total subject has BMI more than 30.

Table 2: Leptin levels in Male and Female in cases and controls

	Cases	Controls
Male	10.44±6.12	6.58±7.56
Female	22.14±10.22	12.60±9.66
P value	p<0.0001	p=0.0008

Table 2 depicts leptin levels were more in females as compared to males and the differences were statistically significant (p<0.0001) in cases. In control group level of leptin were more in females as compared to males and difference were not significant (p=0.0008)

Table 3: Leptin levels in cases and control:

	Cases N (100)	Controls (100)	p-value
Leptin levels	12.53±8.34	7.09±3.45	p<0.0001

Table 3 depicts leptin levels were elevated in the cases group as compared to controls and the differences were statistically significant (p<0.0001).

Table 4: Comparison of median serum leptin levels with different BMI Groups:

BMI (%)	Median serum Leptin ng/ml	P value
18.5-25(16)	48.66	0.001
25-30(28)	63.52
>30(56)	65.72

Table 4 depicts median serum leptin levels were more in BMI group more than 30 and the differences were statistically significant.

Table 5: Correlation of serum leptin with various parameters of cases group

Correlation of serum leptin with	r-value	p-value
Age	0.480	0.001
Body mass index	0.125	0.178
Waist to hip ratio	0.160	0.098
Fasting blood sugar	0.559	0.001
Total cholesterol	0.278	0.004
Triglycerides	0.121	0.198
HDL	-0.318	0.001
LDL	0.289	0.001
VLDL	0.396	0.001

Table 5 depicts correlation of leptin and various parameters. All the parameters except HDL were positively correlated while HDL was negatively correlated.

DISCUSSION:

Present study observed 64% of subjects were between the age group of 40-60 and mean age was 55.34 ± 2.43years. 56% of the total subject has BMI more than 30 kg/m2. Leptin levels were more in females as compared to males and the differences were statistically significant (p<0.0001) in cases. In the control group levels of leptin were more in females as compared to males and differences were not significant (p=0.0008). Present study observed, leptin levels were elevated in the cases group as compared to controls and the differences were statistically significant (p<0.0001). Similar findings were observed in a study conducted by Diwan et al, [27] where they observed serum leptin levels were elevated in diabetic patients when compared to healthy control groups. Further their study also concluded serum leptin level was significantly higher in obese diabetic patients as compared to non obese healthy controls. Study conducted in Italy by TattiP et al.,[28] also observed a high level of serum leptin in diabetic patients as compared to non diabetic groups. Mcneely MJ et al., study conducted on Japanese population showed that an increase in leptin levels was associated with increased risk for the development of diabetes in men but not in women. On the basis of the above finding it is clear that prevalence of high levels of serum leptin is associated with diabetes. Haffner et al studied mexican Americans and found that leptin concentrations were not having 2any association with diabetes. As they found components of obesity were similar in both diabetic and non diabetic subjects. [16, 29, 30] In present study leptin levels were elevated in the cases group as compared to controls and the differences were statistically significant (p<0.0001).

Present study observed a higher level of leptin in patients with BMI more than or equal to 30 kg/m2. Maffei M et al study conducted in the United States of America observed the plasma leptin levels were highly correlated with BMI [7, 31]. Al maskari MY et al., study observed significant differences in serum leptin levels in obese and non-obese healthy participant and also showed significant differences in levels of serum leptin in obese group of participant with weight p=0.002, body fat percentage p=0.0001 and BMI p=0.0001 in population of Oman. [16]. Present study results when correlated with leptin and BMI showed (r=0.125, p=0.178) was nearly similar to study conducted by Gawali R et al study. While another study conducted in Mumbai by Lele Rd et al., observed leptin level, waist circumference and BMI among diabetic and healthy control and found significant differences (p<0.0001). [12, 31]

Present study when correlation of leptin and various parameters were done. All the parameters except LDL were positively correlated while HDL was negatively correlated. Waist to hip ratio was correlated and there were no statistically significant differences in present study.

When lipid profile was correlated with leptin, LDL and VLDL were observed having significant differences and were positively correlated. While TCH and Triglycerides were having no significant correlation. Studies conducted in the USA and UK reported significant positive correlation between serum leptin and TG. [32,33] Brennan AM et al., study observed serum leptin and adipocyte dysfunction in presence of increased BMI, LDL and TG are associated with each other. [34]

CONCLUSION:

Present study concludes serum leptin level was significantly elevated in patients with diabetes when compared to non diabetics healthy control group. And one thing to observe was cases with increased BMI were more prone to have a high level of BMI. serum leptin levels were more in females as compared to males, which may be helpful for future studies. at last we conclude leptin levels are associated with diabetes and obesity, somehow. Further study should be conducted in large numbers of the population.

CONFLICT OF INTEREST:

Nil.

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Received on 21.08.2020 Modified on 20.09.2020

Research J. Pharm. and Tech. 2020; 13(12):6295-6299.

DOI: 10.5958/0974-360X.2020.01095.1