Globally, diabetes mellitus (DM) is a growing medical and social problem. It is estimated that the number of people affected by diabetes will rise from 463 million in 2019 to 700 million by 2045 [1]. Vascular complications lead to increased morbidity and mortality of these patients. The incidence is growing of diabetic microvascular complications, including diabetic retinopathy (DR), diabetic polyneuropathy (DPN), and diabetic nephropathy (DN) [2, 3, 4]. The pathological mechanisms that are responsible for developing these complications are very complex and not fully understood. It seems that genetic susceptibility plays a role in developing such complications [5]. It has been postulated that zinc-dependent endopeptidases called matrix metalloproteinases (MMPs), are very important in remodelling the extracellular matrix, and therefore they have an impact on the onset and progression of diabetic vascular complications [6, 7]. The regulation of MMPs is very complex, depending not only on the regulation of their tissue inhibitors, but also on the regulation of MMP gene expressions by transcriptional factors and epigenetic modifications [8]. Matrix metalloproteinase-2 (
Diabetic retinopathy is a very common microvascular diabetic complication, affecting up to one third of patients with diabetes [9, 10]. It can lead to seriuous vision impairments and vision loss, especially in the adult working population [11]. The duration of diabetes and poor metabolic control, as well as elevated blood pressure can contribute to the development of DR [12, 13, 14]. Genetic factors also seem to have an important role, and they account for 25% to 50 % of the risk of developing DR [15]. The role of
Diabetic polyneuropathy (DP) is the most prevalent diabetic complication which affects almost half of the patients with diabetes [22]. It can lead to major disability due to foot amputation, and DP significantly reduces the quality of life [23]. It has been shown that MMPs and their inhibitors may have a role in the process of the demyelization and the regeneration of axons [24, 25].
A single genetic study has shown that SNP -1562C>T in the promoter of the
Diabetic nephropathy (DN) develops in 20-40 % patients with diabetes [28] and is the leading cause of end-stage renal disease [29]. Genetic studies regarding the association of MMP gene polymorphism and DN provide conflicting results. Some show that certain polymorphisms of
The objectives of our study were to assess the frequencies of the
This study contained 102 subjects with type 2 diabetes who were at the Zvezdara University Medical Center from February 2016 to April 2018. The diagnosis of DM was established using the criteria of the World Health Organization (WHO). The presence of microvascular diabetes complications was investigated in all patients on the basis of medical history, laboratory analysis and physical examination. Detailed ophthalmological examination and fundoscopy were done in order to confirm retinal changes due to diabetes. Classification was done to distinguish between nonproliferative retinopathy and proliferative retinopathy. The diagnosis of nephropathy was established based on urine albumin excretion in 24h urine. The cut off value was 30 mg/24h. A comprehensive diabetic foot examination comprising of visual inspection, monofilament examination, pinprick sensation, and ankle reflexes was performed in order to establish the diagnosis of diabetic polyneuropathy.
The control group was comprised of 56 healthy subjects who were recruited during their regular annual health assessments. The local Ethics Committee gave permission to conduct the study and each participant signed informed consent.
Apart from demographic variables (gender and age), additional information regarding the duration of diabetes, antidiabetic medications, and smoking history was collected. Anthropometric variables included measurements of height, weight, and body mass index (BMI). The BMI was calculated according to the following formula: BMI (kg/m2) ꞊ body weight (kg)/ height (m2).
Metabolic variables included measurements of fasting blood glucose (FBG), total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, total triglycerides, serum creatinine, and glycosylated hemoglobin (HbA1c). Peripheral blood samples were taken from the patients with type 2 diabetes and the control subjects after overnight fasting for at least 8 hours and metabolic parameters were analyzed using the biochemical analyzer Olimpus AU680. Detection of the
Statistical analysis was performed using Statistical Package for Social Sciences 20.0 (SPSS Inc., Chicago, Illinois, USA). Descriptive statistics were computed as mean values and standard deviations for continuous variables, and as absolute frequencies and percentage values for categorical variables.
The association between the
The study population included 102 diabetic patients, 65 men and 37 women, aged 61.4 ± 7.3 years with a mean BMI 28.8±4.8kg m2. The mean duration of diabetes was 10.1±5.8 years. Most of the patients were on metformin (86.3 %), 22.5 % on oral antidiabetic drug (OAD), 13.7 % on insulin and 63.7 % on an OAD/insulin combination. The basic demographic features of patients with diabetes are shown in the Table 1. The control group included 56 patients who did not differ in basic demographic characteristics.
Demographic and clinical characteristics of patients.
Variable | Values |
---|---|
Age, mean± SD | 61.4 ± 7.3 |
Gender, male n (%) female n ( %) | 65 (63.7) 37 (36.3) |
Smokers, n (%) | 23 (22.5) |
Diabetes duration, mean± SD | 10.1±5.8 |
BMI, mean± SD | 28.8±4.8 |
HbA1c, mean± SD | 9.40±2.22 |
FBG, mean± SD | 6.90±1.94 |
Total cholesterol (mmol/l), mean± SD | 5.20±1.35 |
LDLc (mmol/l), mean± SD | 3.11±1.03 |
HDLc (mmol/l), mean± SD | 1.15±0.30 |
Triglycerides (mmol/l), mean± SD | 2.25±1.16 |
Albumin mg/24h/urine, mean± SD | 12.54±2.79 |
Serum creatinine (μmol/l), mean± SD | 87.81±42.75 |
OAD only, n (%) | 23 (22.5) |
Insulin only, n (%) | 14 (13.7) |
OAD + insulin, n (%) | 65 (63.7) |
Metformin, n (%) | 88 (86.3) |
Retinopathy non-proliferative, n (%) | 21 (20.6) |
Retinopathy proliferative, n (%) | 9 (8.8) |
Polyneuropathy, n (%) | 40 (39.2) |
Nephropathy, n (%) | 11 (10.8) |
In this study, the
Genotype distrubution of the
Genotype | Patients n (%) | Controls n (%) | P-value OR (95 % CI) patients vs. control * |
---|---|---|---|
-1306CC | 53 (67.1) | 27 (48) | 0.028 |
-1306CT | 24 (30.4) | 25 (45) | 0.457 (0.226-0.932) |
-1306TT | 2 ( 2.5) | 4 (7) | |
-1562CC | 56 (71) | 40 (71) | 0.945 |
-1562CT | 20 (25) | 16 (29) | 1.27 (0.482-2.187) |
-1562TT | 3 (4) | 0 (0) |
* The dominant model of inheritance was examined (carriers of -1306CC genotype vs. carriers of -1306CT or -1306TT genotype; carriers of -1562CC genotype vs. carriers of -1562CT or -1562TT genotype).
Based on data given in table 2, the frequencies of the -1306C and -1306T alleles in the group of diabetic patients are 0.82 and 0.18, respectively. In the control group, the frequencies of these alleles are 0.71 for -1306C and 0.29 for -1306T. In the group of diabetic patients, the frequencies of -1562C and -1562T alleles are 0.84 and 0.16, respectively; in the control group their frequencies are 0.86 and 0.14, respectively.
For the analyzed alleles, Hardy-Weinberg equilibrium testing was performed. The testing showed that the p value of Pearson’s Chi-Square test for
The association of
Genotype frequencies of the
The
In order to assess the impact of both variants on microvascular complications, the alleles’ frequencies were correlated with the presence of diabetic retinopathy, polyneuropathy, and nephropathy in patients with type 2 diabetes. The
Correlation of the
Genotype | Patients n (%) | Controls n ( %) | p-value or (95 % CI) |
---|---|---|---|
-1306CC | 22 (75.86) | 27 (48.21) | 0.0170٭ |
-1306TC and -1306TT | 7 (24.14) | 29 (51.79) | 0.2962 (0.1091-0.8045) |
The
In our study, our primary goal was to assess the possible differences in
To our knowledge, this is the first study investigating
Regarding DR and a possible genetic background, Singh K. et al. postulated that the functional SNP -1562C>T in the promoter of the
A statistically significant difference was observed in both allele and genotype distributions, but only between patients with proliferative retinopathy versus healthy controls with no DM. There were, however, no significant differences between patients with DM, no matter if they have DR or not. This is the same result as our study. Due to the limited number of patients with proliferative retinopathy we were not able to establish if there is a significant difference between these patients and healthy controls.
In another study, Beranek M. et al. showed that plasma levels of
MMPs are regarded as very important players in the development of diabetic polyneuropathy, not only by causing extracellular matrix abnormalities but also by causing neuronal injury which leads to the development of neuropathic pain. So far, no genetic study has been performed regarding MMP gene variants and the presence of DPN. Our results showed that the presence of the
We found no correlation between either
In conclusion, our study showed that the variant -1306C>T in the