Association of obesity in T2DM with differential polymorphism of ghrelin, growth hormone secretagogue receptor-1 and telomeres maintenance genes.

BACKGROUND: Although obesity and T2DM comorbidity is too frequent, the molecular basis of diabetic obesity is largely unexplained and barely investigated. MATERIALS: Cross-sectional studies were conducted in Kingdom of Saudi Arabia (KSA) in 2013 and Kuwait in 2019. Fasting blood samples were obtained from a total of 216 T2DM patients (104 from KSA) and 193 nondiabetic subjects (93 from KSA) after their consents. Eight SNPs in 5 genes known to be associated with both obesity and T2DM, ghrelin (GHRL) and growth hormone secretagogue receptor -GHSR (KSA) and telomeres maintenance genes (Kuwait) were genotyped by rtPCR. Both patients and controls were grouped into obese and non-obese and sub-grouped into 4-BMI- grades: normal, overweight (OW), obese (OBS) and severely obese (SOBS). RESULTS: Showed that the only SNP which was distinguished between all groups/subgroups in all study subjects was the ACYP2 rs6713088G/C, where the common CC genotype was under-expressed in the obese compared to non-obese diabetics (17.8% vs. 40.4%, p 0.01) and between the 4-BMI-grade (p 0.025). Interestingly the same genotype was over-expressed in obese compared to non-obese non-diabetics (50% vs. 27.6%, p 0.04). Furthermore, the GHRL (rs27647C/T), GHSR (rs509030G/C) and TERC (rs12696304G/C) MAFs were significantly low in normal BMI patients; p=0.034, 0.008 and 0.011, respectively. CONCLUSIONS: This is the first report about the molecular distinction between the obese and non-obese diabetics, it showed the association of rs6713088G/C mutant allele with diabetic obesity, while the GHRL, GHSR and TERC SNPs were differentially expressed based on the BMI-grades.

Hormonal and metabolic profiles of obese and nonobese type 2 diabetes patients: implications of plasma insulin, ghrelin, and vitamin D levels.

Type 2 diabetes (T2D) is associated with obesity whereas loss of weight is a feature of the disease; however, the two states are not mutually exclusive. Obesity is linked with changes in hormonal activity and overall body metabolism. MATERIALS AND METHODS: In this study, 408 T2D patients were recruited in three distinct studies conducted in Bahrain, Saudi Arabia, and Kuwait in three different intervals between 2001 and 2019. In addition to demographics, glycemic and lipid profiles were obtained in all studies, whereas plasma insulin and HOMA-IR, vitamin D, and ghrelin were analyzed in Saudi Arabia. Different techniques such as chemical auto-analyzer, ELISA, chemiluminescent immunoassay, radioimmunoassay were used. RESULTS: The obese (BMI ≥ 30 kg/m2) compared with nonobese (BMI 18.5 to <30) patients with diabetes were more likely to be women (P < 0.001), smaller in age (P = 0.028), and with shorter disease duration (P = 0.018). Unexpectedly, the glycemic and lipid profiles were consistently comparable between the two groups in the three sites. Furthermore, vitamin D was strikingly lower in obese patients with diabetes (P = 0.007). Finally, plasma ghrelin (P = 0.163), insulin (P = 0.063), and HOMA-IR (P = 0.166) were comparable between obese and nonobese patients with diabetes. CONCLUSION: Diabetic obesity was significantly associated with female sex, young age, short disease duration, and noticeably low vitamin D, and a trend of high insulin levels. However, the obese and nonobese patients had comparable metabolic profiles with no differences in insulin resistance and ghrelin levels. Further studies, especially at a molecular level, are needed to explore this topic which is barely investigated.

Establishment of reference intervals for immunoassay analytes of adult population in Saudi Arabia.

Background This is a second part of report on the IFCC global multicenter study conducted in Saudi Arabia to derive reference intervals (RIs) for 20 immunoassay analytes including five tumor makers, five reproductive, seven other hormones and three vitamins. Methods A total of 826 apparently healthy individuals aged ≥18 years were recruited in three clinical laboratories located in western, central and eastern Saudi Arabia using the protocol specified for the global study. All serum specimens were measured using Abbott, Architect analyzers. Multiple regression analysis (MRA) was performed to explore sources of variation of each analyte: age, body mass index (BMI), physical exercise and smoking. The magnitude of variation of reference values (RVs) attributable to sex, age and region was calculated by ANOVA as a standard deviation ratio (SDR). RIs were derived by the parametric (P) method. Results MRA revealed that region, smoking and exercise were not relevant sources of variation for any analyte. Based on SDR and actual between-sex differences in upper limits (ULs), we chose to partition RIs by sex for all analytes except for α-fetoprotein and parathyroid hormone (PTH). Age-specific RIs were required in females for ferritin, estradiol, progesterone, testosterone, follitropin, luteotropin and prolactin (PRL). With prominent BMI-related increase, RIs for insulin and C-peptide were derived after excluding individuals with BMI > 32 kg/m2. Individuals taking vitamin D supplements were excluded in deriving RIs for vitamin D and PTH. Conclusions RIs of major immunoassay analytes specific for Saudi Arabians were established in careful consideration of various biological sources of variation.

Leu72Met and Other Intronic Polymorphisms in the GHRL and GHSR Genes Are Not Associated with Type 2 Diabetes Mellitus, Insulin Resistance, or Serum Ghrelin Levels in a Saudi Population.

BACKGROUND: Ghrelin (GHRL), a gastric peptide encoded by the GHRL gene, is known to be involved in energy homeostasis via its G protein receptor, encoded by the growth hormone secretagogue receptor (GHSR) gene. Some studies have shown associations between plasma GHRL levels and GHRL single-nucleotide polymorphisms (SNPs), namely the Leu72Met polymorphism (rs696217 TG), with type 2 diabetes mellitus (T2DM) and insulin resistance (IR), while others have not. The controversies in these associations raise the issue of 'which SNPs in which populations.' The aim of this study was to investigate whether SNPs in GHRL and/or GHSR genes were associated with T2DM, IR, or plasma GHRL levels among Arab Saudis. METHODS: Blood was collected from 208 Saudi subjects with (n=107) and without (n=101) T2DM. DNA samples from these subjects were analyzed by real-time polymerase chain reaction to genotype five intronic SNPs in the GHRL (rs696217 TG, rs27647 CT, rs2075356 CT, and rs4684677 AT) and GHSR (rs509030 GC) genes. In addition, plasma GHRL levels were measured by a radioimmunoassay. RESULTS: None of the SNPs were associated with T2DM, IR, or plasma GHRL levels. The frequencies of the alleles, genotypes, and haplotypes of the five SNPs were comparable between the T2DM patients and the non-diabetic subjects. A large number of the GHRL haplotypes indicates the molecular heterogeneity of the preproghrelin gene in this region. CONCLUSION: Neither the Leu72Met polymorphism nor the other intronic GHRL and GHSR SNPs were associated with T2DM, IR, or GHRL levels. Further investigations should be carried out to explain the molecular basis of the association of the GHRL peptide with T2DM and IR.

Association of Plasma Ghrelin Levels with Insulin Resistance in Type 2 Diabetes Mellitus among Saudi Subjects.

BACKGROUND: Although the exact mechanism of insulin resistance (IR) has not yet been established, IR is the hallmark characteristic of type 2 diabetes mellitus (T2DM). The aim of this study was to examine the relationship between plasma ghrelin levels and IR in Saudi subjects with T2DM. METHODS: Patients with T2DM (n=107, cases) and non-diabetic apparently healthy subjects (n=101, controls) from Saudi Arabia were included in this study. The biochemical profiles and plasma insulin levels of all subjects were analyzed, and IR was estimated using the homeostatic model assessment of insulin resistance (HOMA-IR) index. Active ghrelin levels in plasma were measured using the radioimmunoassay technique. RESULTS: Only 46.7% (50 of 107) of the T2DM subjects had IR, including 26% (28 of 107) with severe IR (HOMA-IR ≥5), while 5.9% (six of 101) of the controls had moderate IR (3 ≤HOMA-IR <5). HOMA-IR values were not associated with age, disease duration, or gender. Importantly, T2DM itself and the co-occurrence of IR with T2DM were significantly associated with low plasma ghrelin levels. However, ghrelin levels were inversely correlated with the HOMA-IR index, body weight, and fasting plasma insulin levels, mainly in the control subjects, which was indicative of the breakdown of metabolic homeostasis in T2DM. CONCLUSION: The prevalence of IR was relatively low, and IR may be inversely associated with plasma ghrelin levels among Saudi patients with T2DM.