Abdominal fat depots and their association with insulin resistance in patients with type 2 diabetes.

BACKGROUND: Asian-Indians show thin fat phenotype, characterized by predominantly central deposition of excess fat. The roles of abdominal subcutaneous fat (SAT), intra-peritoneal adipose tissue, and fat depots surrounding the vital organs (IPAT-SV) and liver fat in insulin resistance (IR), type-2 diabetes (T2D) and metabolic syndrome (MetS) in this population are sparsely investigated. AIMS AND OBJECTIVES: Assessment of liver fat, SAT and IPAT-SV by MRI in subjects with T2D and MetS; and to investigate its correlation with IR, specifically according to different quartiles of HOMA-IR. METHODS: Eighty T2D and the equal number of age sex-matched normal glucose tolerant controls participated in this study. Abdominal SAT, IPAT-SV and liver fat were measured using MRI. IR was estimated by the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). RESULTS: T2D and MetS subjects have higher quantity liver fat and IPAT-SV fat than controls (P = 9 x 10-4 and 4 x 10-4 for T2D and 10-4 and 9 x 10-3 for MetS subjects respectively). MetS subjects also have higher SAT fat mass (P = 0.012), but not the BMI adjusted SAT fat mass (P = 0.48). Higher quartiles of HOMA-IR were associated with higher BMI, W:H ratio, waist circumference, and higher liver fat mass (ANOVA Test P = 0.020, 0.030, 2 x 10-6 and 3 x 10-3 respectively with F-values 3.35, 3.04, 8.82, 4.47 respectively). In T2D and MetS subjects, HOMA-IR showed a moderately strong correlation with liver fat (r = 0.467, P < 3 x 10-5 and r = 0.493, P < 10-7), but not with SAT fat and IPAT-SV. However, in MetS subjects IPAT-SV fat mass showed borderline correlation with IR (r = 0.241, P < 0.05), but not with the BMI adjusted IPAT-SV fat mass (r = 0.13, P = 0.26). In non-T2D and non-MetS subjects, no such correlation was seen. On analyzing the correlation between the three abdominal adipose compartment fat masses and IR according to its severity, the correlation with liver fat mass becomes stronger with increasing quartiles of HOMA-IR, and the strongest correlation is seen in the highest quartile (r = 0.59, P < 10-3). On the other hand, SAT fat mass tended to show an inverse relation with IR with borderline negative correlation in the highest quartile (r = -0.284, P < 0.05). IPAT-SV fat mass did not show any statistically significant correlation with HOMA-IR, but in the highest quartile it showed borderline, but statistically insignificant positive correlation (P = 0.07). CONCLUSION: In individuals suffering from T2D and MetS, IR shows a trend towards positive and borderline negative correlation with liver fat and SAT fat masses respectively. The positive trend with liver fat tends to become stronger with increasing quartile of IR. Therefore, these findings support the theory that possibly exhaustion of protective compartment's capacity to store excess fat results in its pathological deposition in liver as ectopic fat.

Machine Learning Model Based on Insulin Resistance Metagenes Underpins Genetic Basis of Type 2 Diabetes.

Insulin resistance (IR) is considered the precursor and the key pathophysiological mechanism of type 2 diabetes (T2D) and metabolic syndrome (MetS). However, the pathways that IR shares with T2D are not clearly understood. Meta-analysis of multiple DNA microarray datasets could provide a robust set of metagenes identified across multiple studies. These metagenes would likely include a subset of genes (key metagenes) shared by both IR and T2D, and possibly responsible for the transition between them. In this study, we attempted to find these key metagenes using a feature selection method, LASSO, and then used the expression profiles of these genes to train five machine learning models: LASSO, SVM, XGBoost, Random Forest, and ANN. Among them, ANN performed well, with an area under the curve (AUC) > 95%. It also demonstrated fairly good performance in differentiating diabetics from normal glucose tolerant (NGT) persons in the test dataset, with 73% accuracy across 64 human adipose tissue samples. Furthermore, these core metagenes were also enriched in diabetes-associated terms and were found in previous genome-wide association studies of T2D and its associated glycemic traits HOMA-IR and HOMA-B. Therefore, this metagenome deserves further investigation with regard to the cardinal molecular pathological defects/pathways underlying both IR and T2D.

Clinical and Biochemical Phenotype of Indian Children with Different Types of Idiopathic Growth Hormone Deficiency and their Association with Pituitary Height on MRI.

BACKGROUND AND OBJECTIVES: Differentiation of growth hormone deficiency (GHD) into various types has been made based on peak stimulated growth hormone levels and other hormone axis involvement. The data regarding how this classification is associated with variation in clinical and biochemical phenotype and how these findings associate with pituitary morphology remains sparse, especially in the Indian population. Therefore, we aimed to ascertain the differences in the pattern of auxological, clinical features including pituitary hypoplasia, and endocrinological profile among patients with severe GHD, partial GHD, and MPHD in the Indian population and to evaluate the association of pituitary height with various clinical and hormonal parameters. MATERIALS AND METHODS: We conducted a cross-sectional study in 100 patients with idiopathic GHD. Patients were grouped into severe GHD, partial GHD, and MPHD to observe the differences in clinical, biochemical, and MRI findings. The pituitary height findings were correlated clinical and biochemical presentation. RESULTS: MPHD subjects had a significantly higher frequency of breech delivery, neonatal jaundice, neonatal hypoglycemia, and micropenis. A significant difference was observed in the chronological age, bone age retardation (CA-BA), height SDS, weight SDS, peak GH response, IGF-1, IGF-1 SDS, and prevalence of pituitary hypoplasia, pituitary height, and pituitary height SDS among these three groups. In the composite population of GHD, pituitary height SDS was correlated with peak GH, basal IGF-I SDS, and body height SDS. CONCLUSION: The clinical and biochemical phenotype differs significantly among the various types of GHD. Pituitary height correlates with these findings and is helpful in further assessment of these patients.

Whole transcriptome RNA-seq reveals key regulatory factors involved in type 2 diabetes pathology in peripheral fat of Asian Indians.

The prevalence of Type 2 Diabetes has reached an epidemic proportion particularly in south Asian countries. We have earlier shown that the anatomical fat distribution, termed 'thin fat phenotype' in this population indeed plays a major role for their T2D-predisposition it is indeed the sick fat or adiposopathy, which is the root cause of metabolic syndrome and diabetes and affects both-peripheral, as well as visceral adipose tissue compartments. In present study, we have attempted to unravel the altered regulatory mechanisms at the level of transcription factors, and miRNAs those may likely accounts to T2D pathophysiology in femoral subcutaneous adipose tissue. We prioritized transcription factors and protein kinases as likely upstream regulators of obtained differentially expressed genes in this RNA-seq study. An inferred network of these upstream regulators was then derived and the role of TFs and miRNAs in T2D pathophysiology was explored. In conclusions, this RNS-Seq study finds that peripheral subcutaneous adipose tissue among Asian Indians show pathology characterized by altered lipid, glucose and protein metabolism, adipogenesis defect and inflammation. A network of regulatory transcription factors, protein kinases and microRNAs have been imputed which converge on the process of adipogenesis. As the majority of these genes also showed altered expression in diabetics and some of them are also circulatory, therefore they deserve further investigation for potential clinical diagnostic and therapeutic applications.

Pituitary hypoplasia is the best MRI predictor of the severity and type of growth hormone deficiency in children with congenital growth hormone deficiency.

OBJECTIVES: Congenital idiopathic growth hormone deficiency (GHD) is associated with various MRI abnormalities, including sellar and extrasellar abnormalities. However, it remains contentious whether MRI brain findings could provide an additional avenue for precisely predicting the differentiation of GHD based on severity and type {isolated GHD or multiple pituitary hormone deficiencies (MPHD)}. This study aimed to ascertain the abnormality that is the best predictor of severity and type of GHD amongst the different MRI findings. METHODS: We conducted an analytical cross-sectional study, including 100 subjects diagnosed with idiopathic GHD. Patients were grouped into severe GHD, partial GHD, and MPHD and into groups based on the presence of pituitary hypoplasia, extrasellar brain abnormalities (EBA), and presence of ectopic posterior pituitary or pituitary stalk abnormalities (EPP/PSA) or both. RESULTS: Sixty six percentage of subjects had isolated GHD, 34% had MPHD, 71% had severe GHD, and 29% had partial GHD. Pituitary hypoplasia was the most common finding, observed in 53% of patients, while 23% had EBA, and 25% had EPP/PSA. Pituitary hypoplasia was observed to be the best predictor of severity of GHD with an odds ratio (OR) of 10.8, followed by EPP/PSA (OR=2.8), and EBA was the weakest predictor (OR=1.8). Pituitary hypoplasia was the only finding to predict MPHD (OR=9.2) significantly. On ROC analysis, a Pituitary height SDS of -2.03 had the best detection threshold for both severe GHD and MPHD. CONCLUSIONS: We observed Pituitary hypoplasia to be not only the most frequent MRI abnormality but also the best predictor of severe GHD and MPHD amongst various sellar and extrasellar abnormalities.

Hyperandrogenism, Insulin Resistance, and Acanthosis Nigricans (HAIR-AN) Syndrome Reflects Adipose Tissue Dysfunction ("Adiposopathy" or "Sick Fat") in Asian Indian Girls.

BACKGROUND: Whether HAIR-AN syndrome and polycystic ovarian syndrome (PCOS) are distinct entities or represent a phenotypic spectrum of the same syndrome is still unclear. HAIR-AN syndrome is characterized by high insulin resistance, obesity, and hyperinsulinemia as compared to PCOS and could represent adipose tissue dysfunction as the primary pathophysiologic trigger. This study was undertaken to study the role of adipose tissue dysfunction in HAIR-AN syndrome and PCOS using adipocytokines as surrogate markers of "adiposopathy." MATERIALS AND METHODS: A cross-sectional observational study was conducted at a tertiary care hospital over a period of 1 year. Serum adiponectin, leptin, IL-6, and TNF-α levels were measured in 30 women with HAIR-AN syndrome and in 30 women with PCOS. Correlations between adipocytokines, inflammatory markers, serum testosterone, and serum insulin were determined. Data analysis was performed using the SPSS version 23.0 (IBM SPSS Statistics Inc., Chicago, IL, USA) software program. RESULTS: Women with HAIR-AN syndrome had significantly higher hyperandrogenemia, hyperinsulinemia, and insulin resistance as compared to PCOS women. They also had high leptin levels and lower adiponectin levels (p < 0.001). However, the levels of inflammatory markers (TNF-α and IL-6) were similar in both the groups (p > 0.05). Serum adiponectin showed a negative correlation with HOMA-IR and testosterone levels, while leptin showed a positive correlation with both in HAIR-AN patients while no such correlation was found in the PCOS group. CONCLUSION: The significantly raised adipocytokines in HAIR-AN syndrome patients as compared to PCOS patients indicates the primary role of adipose tissue dysfunction ("adiposopathy") in the pathogenesis of HAIR-AN syndrome while only a minor role, if any, in PCOS. Both these syndromes stand as distinct entities pathogenically with an overlapping phenotype.

The Transcriptomic Evidence on the Role of Abdominal Visceral vs. Subcutaneous Adipose Tissue in the Pathophysiology of Diabetes in Asian Indians Indicates the Involvement of Both.

The roles of abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) in the molecular pathogenesis type-2 diabetics (T2D) among Asian Indians showing a "thin fat" phenotype largely remains obscure. In this study, we generated transcription profiles in biopsies of these adipose depots obtained during surgery in 19 diabetics (M: F ratio, 8:11) and 16 (M: F ratio 5:11) age- and BMI-matched non-diabetics. Gene set enrichment analysis (GSEA) was used for comparing transcription profile and showed that 19 gene sets, enriching inflammation and immune system-related pathways, were upregulated in diabetics with F.D.R. <25% and >25%, respectively, in VAT and SAT. Moreover, 13 out of the 19 significantly enriched pathways in VAT were among the top 20 pathways in SAT. On comparison of VAT vs. SAT among diabetics, none of the gene sets were found significant at F.D.R. <25%. The Weighted Gene Correlation Analysis (WGCNA) analysis of the correlation between measures of average gene expression and overall connectivity between VAT and SAT was significantly positive. Several modules of co-expressed genes in both the depots showed a bidirectional correlation with various diabetes-related intermediate phenotypic traits. They enriched several diabetes pathogenicity marker pathways, such as inflammation, adipogenesis, etc. It is concluded that, in Asian Indians, diabetes pathology inflicts similar molecular alternations in VAT and SAT, which are more intense in the former. Both adipose depots possibly play a role in the pathophysiology of T2D, and whether it is protective or pathogenic also depends on the nature of modules of co-expressed genes contained in them.

The common pathophysiologic threads between Asian Indian diabetic's 'Thin Fat Phenotype' and partial lipodystrophy: the peripheral adipose tissue transcriptomic evidences.

T2D is a complex disease with poorly understood mechanisms. In Asian Indians, it is associated with "thin fat" phenotype which resembles with partial lipodystrophy. We hypothesized that disturbed expression of lipodystrophy genes might play a role in T2D pathogenesis. Therefore, we attempted to establish a link between these two diseases by studying the overlap between the network of lipodystrophy genes and the differentially expressed genes (DEGs) in the peripheral subcutaneous adipose tissue of Asian Indians diabetics. We found that 16, out of 138 lipodystrophy genes were differentially regulated in diabetics and around 18% overlap between their network and the DEGs; the expression level of lipodystrophy genes showed an association with disease-related intermediate phenotypic traits among diabetics but not in the control group. We also attempted to individualize the diabetic patients based on ±2 fold altered expression of lipodystrophy genes as compared to their average expression in the control group. In conclusion, significant overlap exists between some of the lipodystrophy genes and their network with DEGs in the peripheral adipose tissue in diabetics. They possibly play a role in the pathogenesis of diabetes and individualization of diabetics is possible based on their altered expression in their peripheral adipose tissue.

Multifaceted genome-wide study identifies novel regulatory loci in SLC22A11 and ZNF45 for body mass index in Indians.

Obesity, a risk factor for multiple diseases (e.g. diabetes, hypertension, cancers) originates through complex interactions between genes and prevailing environment (food habit and lifestyle) that varies across populations. Indians exhibit a unique obesity phenotype with high abdominal adiposity for a given body weight compared to matched white populations suggesting presence of population-specific genetic and environmental factors influencing obesity. However, Indian population-specific genetic contributors for obesity have not been explored yet. Therefore, to identify potential genetic contributors, we performed a two-staged genome-wide association study (GWAS) for body mass index (BMI), a common measure to evaluate obesity in 5973 Indian adults and the lead findings were further replicated in 1286 Indian adolescents. Our study revealed novel association of variants-rs6913677 in BAI3 gene (p = 1.08 × 10-8) and rs2078267 in SLC22A11 gene (p = 4.62 × 10-8) at GWAS significance, and of rs8100011 in ZNF45 gene (p = 1.04 × 10-7) with near GWAS significance. As genetic loci may dictate the phenotype through modulation of epigenetic processes, we overlapped genetic data of identified signals with their DNA methylation patterns in 236 Indian individuals and performed methylation quantitative trait loci (meth-QTL) analysis. Further, functional roles of discovered variants and underlying genes were speculated using publicly available gene regulatory databases (ENCODE, JASPAR, GeneHancer, GTEx). The identified variants in BAI3 and SLC22A11 genes were found to dictate methylation patterns at unique CpGs harboring critical cis-regulatory elements. Further, BAI3, SLC22A11 and ZNF45 variants were located in repressive chromatin, active enhancer, and active chromatin regions, respectively, in human subcutaneous adipose tissue in ENCODE database. Additionally, these genomic regions represented potential binding sites for key transcription factors implicated in obesity and/or metabolic disorders. Interestingly, GTEx portal identify rs8100011 as a robust cis-expression quantitative trait locus (cis-eQTL) in subcutaneous adipose tissue (p = 1.6 × 10-7), and ZNF45 gene expression in skeletal muscle of Indian subjects showed an inverse correlation with BMI indicating its possible role in obesity. In conclusion, our study discovered 3 novel population-specific functional genetic variants (rs6913677, rs2078267, rs8100011) in 2 novel (SLC22A11 and ZNF45) and 1 earlier reported gene (BAI3) for BMI in Indians. Our study decodes key genomic loci underlying obesity phenotype in Indians that may serve as prospective drug targets in future.

Functional Interactomes of Genes Showing Association with Type-2 Diabetes and Its Intermediate Phenotypic Traits Point towards Adipo-Centric Mechanisms in Its Pathophysiology.

The pathogenic mechanisms causing type 2 diabetes (T2D) are still poorly understood; a greater awareness of its causation can lead to the development of newer and better antidiabetic drugs. In this study, we used a network-based approach to assess the cellular processes associated with protein-protein interaction subnetworks of glycemic traits-HOMA-ß and HOMA-IR. Their subnetworks were further analyzed in terms of their overlap with the differentially expressed genes (DEGs) in pancreatic, muscle, and adipose tissue in diabetics. We found several DEGs in these tissues showing an overlap with the HOMA-ß subnetwork, suggesting a role of these tissues in ß-cell failure. Many genes in the HOMA-IR subnetwork too showed an overlap with the HOMA-ß subnetwork. For understanding the functional theme of these subnetworks, a pathway-to-pathway complementary network analysis was done, which identified various adipose biology-related pathways, containing genes involved in both insulin secretion and action. In conclusion, network analysis of genes showing an association between T2D and its intermediate phenotypic traits suggests their potential role in beta cell failure. These genes enriched the adipo-centric pathways and were expressed in both pancreatic and adipose tissue and, therefore, might be one of the potential targets for future antidiabetic treatment.

Correlation of Olfactory Phenotype by Indian Smell Identification Test and Quantitative MRI of Olfactory Apparatus in Idiopathic Hypogonadotropic Hypogonadism.

OBJECTIVES: Idiopathic hypogonadotropic hypogonadism (IHH) can be associated with anosmia/hyposmia. The objective of this study is to evaluate olfaction by Indian smell identification test (INSIT) and measure olfactory bulbs (OBs) and sulci using dedicated magnetic resonance imaging (MRI) in patients with IHH and correlate MRI findings with INSIT. METHODS: Forty patients with IHH underwent (a) brief smell identification test (INSIT) and (b) MRI of the olfactory apparatus. The size of olfactory sulcus and bulb was quantified and compared with the normative data obtained in 22 controls. The agreement between INSIT and MRI was assessed using Kappa index. RESULTS: Of the 40 patients, 8 patients who reported abnormal smell sensation and 12 of the remaining 32 patients who reported normal smell sensation historically had a low score on INSIT. Thus, there were 20 patients with Kallmann syndrome (KS) and the rest 20 were normosmic IHH (nIHH). Of 40 patients with IHH, MRI finding was suggestive of normal (n = 16), hypoplastic (n = 12), and aplastic (n = 12) olfactory apparatus. All 20 patients with KS have olfactory abnormalities (n = 12 aplastic, n = 8 hypoplastic), and 4 of 20 nIHH have olfactory abnormalities (hypoplastic only) on MRI. There is (a) significant positive correlation (r = 0.54, P = 0.013) between the OB volume (MRI) and smell test scores and (b) moderate agreement (Kappa index: 0.49) between smell defect (INSIT score ≤ 4) and aplastic olfactory apparatus. CONCLUSION: Self-reporting of smell significantly underestimates olfactory phenotype, and hence we recommend an objective smell test to differentiate KS from nIHH. Olfactory phenotype significantly correlates with MRI quantification of olfactory apparatus in IHH.

Transcriptome profiling reveals association of peripheral adipose tissue pathology with type-2 diabetes in Asian Indians.

Type 2 diabetes (T2D) is a complex disease with an elusive link between its molecular aetiology and clinical presentation. Although, the role of visceral adipose tissue in insulin-resistance and T2D is known, limited information is available on the role of peripheral-subcutaneous adipose tissue especially in Asian Indians. In this microarray-based study of diabetic and normal glucose tolerant Asian Indians, we generated the transcriptome of their thigh adipose tissue and analyzed differentially expressed genes (DEGs) using weighted gene co-expression network analysis; further we identified perturbed pathways implicated by these DEGs in relevant co-expression modules. We also attempted to link these pathways with known aspects of T2D pathophysiology in terms of their association with some of their intermediate traits, namely; adipocyte size, HOMA-B, HOMA-R, Hb1Ac, insulin, glucose-level, TNF-α, IL-6, VLDLs, LDLs, HDLs, and NEFAs. It was observed that several modules of co-expressed genes show an association with diabetes and some of its intermediate phenotypic traits mentioned above. Therefore, these findings suggest a role of peripheral subcutaneous adipose tissue in the pathophsiology of T2D in Asian Indians. Additionally, our study indicated that the peripheral subcutaneous adipose tissue in diabetics shows pathologic changes characterized by adipocyte hypertrophy and up-regulation of inflammation-related pathways.

Genetics of Lipodystrophy: Can It Help in Understanding the Pathophysiology of Metabolic Syndrome?

Understanding phenotypes and their genetic determinants for metabolic syndrome (MetS) has been quite challenging. With the advent of systems genomic approaches, there is a need to decipher methods for identification and evaluating the functional role of phenotypic traits associated with complex diseases, such as MetS. The monogenic syndromes of lipodystrophy are well understood, but the molecular pathophysiology of insulin resistance (IR) underpinning the obesity, diabetes mellitus, and dyslipidemia is not well deciphered. In this commentary, we argue the role of pathophysiology of MetS, and its effects into possible understanding of genetic determinants associated with lipodystrophy-mediated diabetes mellitus.

Application of Chromosomal Microarray for Evaluation of Idiopathic Short Stature in Asian Indian Children: A Pilot Study.

BACKGROUND: Human height is a classic polygenic trait and currently available data explains only 10% of the phenotypic variation in height. Almost 60%-80% of the children coming to pediatric and endocrinology outpatient department for the evaluation of short stature are still labeled as idiopathic. OBJECTIVES: The aim of this study is to identify various chromosomal alterations causing idiopathic short stature (ISS) and short stature with dysmorphic features not pertaining to known genetic syndromes. MATERIALS AND METHODS: After exclusion of all nutritional, systemic, endocrine, and syndromic causes of short stature, 19 patients with height <2 standard deviation scores were subjected to chromosomal microarray (CMA) study using Affymetrix CytoScan 750K array and CMA Scanner 3000 platform. RESULTS: We identified total 61 copy-number variant (CNV) and polymorphs (33 gains, 11 loss, and 17 gain-mosaics) not described as normal variants in database of genomic variations. We identified SHOX haploinsufficiency as a cause of short stature in two patients, whereas one patient was gain-mosaic for SHOX. All three had normal conventional karyotype. One of these patients also had deletion of PAX3, which could be the cause of both short stature and associated mild intellectual impairment in this patient. We also found a long noncoding RNA, namely, KIAA0125 and a pseudogene ADAM6 in 18 out of our 19 patients which might have a regulatory role. CONCLUSION: This study shows that CMA is a very promising tool for the identification of pathogenic CNVs in patients with ISS. It can also help to identify novel genes controlling height and can open up new insight into pathophysiologic mechanisms underlying ISS, and thus may help to unfold new therapeutic targets for treatment of this condition. The association of CNV having genes for long noncoding RNAs, such as KIAA0125 and pseudogene such as ADAM6 with ISS suggest that they may play a role in controlling the expression of height-related genes and it needs further investigations.

Systems Genomics of Thigh Adipose Tissue From Asian Indian Type-2 Diabetics Revealed Distinct Protein Interaction Hubs.

We performed a systematic analysis of genes implicated in thigh subcutaneous adipose tissue of Asian Indian Type 2 Diabetes Mellitus (AIT2DM) and created a phenome-interactome network. This analysis was performed on 60 subjects specific to limb thigh fat by integrating phenotypic traits and similarity scores associated with AIT2DM. Using a phenotypic attribute, a contextual neighbor was identified across all the traits, viz. body mass index (BMI) statistics, adipocyte size, lipid parameters, homeostatic model assessment- insulin resistance (HOMA-IR), HOMA-ß. In this work, we have attempted to characterize transcription signatures using the phenome-interactome maps where each of the traits under study including the intermediary phenotypes has a distinct set of genes forming the hubs. Furthermore, we have identified various clinical, biochemical, and radiological parameters which show significant correlation with distinct hubs. We observed a number of novel pathways and genes including those that are non-coding RNAs implicated in AIT2DM.We showed that they appear to be associated with pathways, viz. tyrosine kinase JAK2, NOTCH thereby recruiting signaling molecules such as STAT5 and Src family kinases on the cell surface regulated them and our analyses comprising significant hubs suggest that thigh subcutaneous adipose tissue plays a role in pathophysiology of AIT2DM.

Osteoporosis in Otherwise Healthy Patients with Type 2 Diabetes: A Prospective Gender Based Comparative Study.

BACKGROUND AND OBJECTIVE: Type 2 diabetes mellitus (T2DM) may affect bone loss differentially in adult males and postmenopausal females. We evaluated the prevalence of osteoporosis in otherwise healthy adults with T2DM. MATERIALS AND METHODS: In a cross-sectional study, adults with T2DM, aged 50 years and above, were evaluated for bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA) scan at spine and hip. T-score of ≤-2.5 was defined as osteoporosis and score -2.49 to -1.0 as osteopenia at either site. Correlation of low BMD with demographic, clinical, and laboratory parameters including serum Vitamin D and serum testosterone (in males) was evaluated. RESULTS: In 200 patients, mean age was 64.5 ± 7.0 years and age differed significantly in males and females (P < 0.0001). Osteoporosis was present in 35.5% adults with T2DM. Significantly greater proportion of females had osteoporosis (49.5% vs. 22.3%, P < 0.0001). Frequency of osteoporosis at spine (33.5%) was higher than the same at hip (13.5%). Compared to males, significantly greater proportion of females had osteoporosis and osteopenia at both spine (P < 0.0001) and hip (P < 0.0001). Among all parameters assessed, a significant positive correlation of T-score at spine and hip was seen with body mass index in both males (r = 0.287, P = 0.003 at spine and r = 0.421, P < 0.0001 at hip) and females (r = 0.291, P = 0.004 at spine and r = 0.280, P = 0.010 at hip). There was no association of Vitamin D deficiency (45.5% patients) with either T-score and presence of osteoporosis either at spine (P = 0.388 and P = 0.177) or hip (P = 0.431 and P = 0.593). CONCLUSION: Prevalence of osteoporosis in otherwise healthy T2DM was 35.5% with greater prevalence in females than males. Body mass but not Vitamin D or testosterone has an important role in the determination of bone loss in T2DM.

Transcriptomic analysis of visceral adipose from healthy and diabetic obese subjects.

Understanding the role of visceral fat accumulation in the occurrence and progression of metabolic syndrome is of considerable interest. In order to understand the difference between visceral tissue biology of healthy and unhealthy obese individuals, we have used microarray profiling to compare genome-wide expression differences between visceral adipose tissue biopsies obtained from obese diabetics, and those from age and body mass index (BMI) matched normal glucose tolerance subjects. Whereas genes upregulated in diabetics showed enrichment of natural killer cell mediated cytotoxicity, the downregulated genes showed enrichment of biosynthesis of unsaturated fatty acids. Given the known inhibitory effect of unsaturated fatty acids on inflammation and natural killer cell number or activity, our results suggest that visceral inflammation resulting from decreased levels of unsaturated fatty acids may underlie progression of diabetes in obese individuals.

Systems biology approach reveals genome to phenome correlation in type 2 diabetes.

Genome-wide association studies (GWASs) have discovered association of several loci with Type 2 diabetes (T2D), a common complex disease characterized by impaired insulin secretion by pancreatic ß cells and insulin signaling in target tissues. However, effect of genetic risk variants on continuous glycemic measures in nondiabetic subjects mainly elucidates perturbation of insulin secretion. Also, the disease associated genes do not clearly converge on functional categories consistent with the known aspects of T2D pathophysiology. We used a systems biology approach to unravel genome to phenome correlation in T2D. We first examined enrichment of pathways in genes identified in T2D GWASs at genome-wide or lower levels of significance. Genes at lower significance threshold showed enrichment of insulin secretion related pathway. Notably, physical and genetic interaction network of these genes showed robust enrichment of insulin signaling and other T2D pathophysiology related pathways including insulin secretion. The network also overrepresented genes reported to interact with insulin secretion and insulin action targeting antidiabetic drugs. The drug interacting genes themselves showed overrepresentation of insulin signaling and other T2D relevant pathways. Next, we generated genome-wide expression profiles of multiple insulin responsive tissues from nondiabetic and diabetic patients. Remarkably, the differentially expressed genes showed significant overlap with the network genes, with the intersection showing enrichment of insulin signaling and other pathways consistent with T2D pathophysiology. Literature search led our genomic, interactomic, transcriptomic and toxicogenomic evidence to converge on TGF-beta signaling, a pathway known to play a crucial role in pancreatic islets development and function, and insulin signaling. Cumulatively, we find that GWAS genes relate directly to insulin secretion and indirectly, through collaborating with other genes, to insulin resistance. This seems to support the epidemiological evidence that environmentally triggered insulin resistance interacts with genetically programmed ß cell dysfunction to precipitate diabetes.

Microarray evidences the role of pathologic adipose tissue in insulin resistance and their clinical implications.

Clustering of insulin resistance and dysmetabolism with obesity is attributed to pathologic adipose tissue. The morphologic hallmarks of this pathology are adipocye hypertrophy and heightened inflammation. However, it's underlying molecular mechanisms remains unknown. Study of gene function in metabolically active tissues like adipose tissue, skeletal muscle and liver is a promising strategy. Microarray is a powerful technique of assessment of gene function by measuring transcription of large number of genes in an array. This technique has several potential applications in understanding pathologic adipose tissue. They are: (1) transcriptomic differences between various depots of adipose tissue, adipose tissue from obese versus lean individuals, high insulin resistant versus low insulin resistance, brown versus white adipose tissue, (2) transcriptomic profiles of various stages of adipogenesis, (3) effect of diet, cytokines, adipokines, hormones, environmental toxins and drugs on transcriptomic profiles, (4) influence of adipokines on transcriptomic profiles in skeletal muscle, hepatocyte, adipose tissue etc., and (5) genetics of gene expression. The microarray evidences of molecular basis of obesity and insulin resistance are presented here. Despite the limitations, microarray has potential clinical applications in finding new molecular targets for treatment of insulin resistance and classification of adipose tissue based on future risk of insulin resistance syndrome.

Glycaemic control in type 2 diabetes mellitus patients undergoing major surgery: comparison of three subcutaneous insulin regimens.

Pre-operative glucose control with subcutaneous insulin in non-urgent situations is logical and well accepted. But the best regimen amongst the many available ones of insulin administration during peroperative period during major surgery is uncertain. We compared three subcutaneous insulin regimens for pre-operative glucose control in type 2 diabetes mellitus (T2DM) patients. One hundred and seventy-two T2DM patients hospitalised for major surgeries were enrolled in the study. Pre-operative glycaemic control was achieved with one of the following regimens: (1) Premix 30/70 insulin (R/N-0-R/N). (2) R + NPH; basal-bolus regular and NPH insulin (R-R-R/N). (3) R + G; basal-bolus regular and glargine insulin (R-R-R-G) [G: glargine insulin; N: neutral protamine hagedorn insulin; R: regular insulin]. Insulin doses were adjusted to achieve fasting and postmeal glucose values respectively <120 and <180 mg/dl. Intra-operative management included glucose insulin potassium solution. Postoperatively, patients were switched back to the same insulin regimen that they received pre-operatively. These regimens were compared for following parameters. (1) Time to achieve glycaemic target. (2) Total daily insulin dose. (3) Incidence of hypo- and severe hyperglycaemia. (4) Complications like renal failure, infection, etc. (5) in hospital mortality. R + G regimen was associated with lesser dose of insulin (29.53 +/- 9.83 versus 35.67 +/- 12.19 and 37.42 +/- 13.5 unit respectively for regimen 2 and 1, p < 0.005), lesser time to achieve glycaemic target (6.75 +/- 3.25 versus 7.37 +/- 7.47 and 8.23 +/- 6.04 days, p > 0.05), lower incidence of hypoglycaemia (10.53 versus 14.81 and 30.00%, p < 0.02) and severe hyperglycaemia (5.26 versus 29.63 and 8.33%, p < 0.005). Incidence of infection (10.53 versus 18.52 and 15.00%, p > 0.05), renal complications (10.53 versus 11.11 and 15.00%, p > 0.05) and mortality (5.26 versus 14.81 and 15.00%, p > 0.05) were lower with this regimen, but the difference was not statistically significant. Premix 30/70 and R + NPH regimens were comparable for most parameters but hypoglycaemia and severe hyperglycaemia were more frequent respectively with premix 30/70 and R + NPH regimens. In contrast to the popular perception about the risk of hypoglycaemia with long acting insulins, insulin analogue glargine was found to be better than NPH insulin in basal bolus regimens in achieving better glycaemic control with fewer incidence of hypoglycaemia.