Current controversies in the mechanisms and treatment of gestational diabetes

Mitochondrial-derived peptides: Antidiabetic functions and evolutionary perspectives

Mitochondrial-derived peptides (MDPs) are a novel class of bioactive microproteins encoded by short open-reading frames (sORF) in mitochondrial DNA (mtDNA). Currently, three types of MDPs have been identified: Humanin (HN), MOTS-c (Mitochondrial ORF within Twelve S rRNA type-c), and SHLP1-6 (small Humanin-like peptide, 1 to 6). The 12 S ribosomal RNA (MT-RNR1) gene harbors the sequence for MOTS-c, whereas HN and SHLP1-6 are encoded by the 16 S ribosomal RNA (MT-RNR2) gene. Special genetic codes are used in mtDNA as compared to nuclear DNA: (i) ATA and ATT are used as start codons in addition to the standard start codon ATG; (ii) AGA and AGG are used as stop codons instead of coding for arginine; (iii) the standard stop codon UGA is used to code for tryptophan. While HN, SHLP6, and MOTS-c are encoded by the H (heavy owing to high guanine + thymine base composition)-strand of the mtDNA, SHLP1-5 are encoded by the L (light owing to less guanine + thymine base composition)-strand. MDPs attenuate disease pathology including Type 1 diabetes (T1D), Type 2 diabetes (T2D), gestational diabetes, Alzheimer's disease (AD), cardiovascular diseases, prostate cancer, and macular degeneration. The current review will focus on the MDP regulation of T2D, T1D, and gestational diabetes along with an emphasis on the evolutionary pressures for conservation of the amino acid sequences of MDPs.

Diabetes and Its Cardiovascular Complications: Comprehensive Network and Systematic Analyses

Diabetes mellitus is a worldwide health problem that usually comes with severe complications. There is no cure for diabetes yet and the threat of these complications is what keeps researchers investigating mechanisms and treatments for diabetes mellitus. Due to advancements in genomics, epigenomics, proteomics, and single-cell multiomics research, considerable progress has been made toward understanding the mechanisms of diabetes mellitus. In addition, investigation of the association between diabetes and other physiological systems revealed potentially novel pathways and targets involved in the initiation and progress of diabetes. This review focuses on current advancements in studying the mechanisms of diabetes by using genomic, epigenomic, proteomic, and single-cell multiomic analysis methods. It will also focus on recent findings pertaining to the relationship between diabetes and other biological processes, and new findings on the contribution of diabetes to several pathological conditions.

Proteomics reveals different pathological processes of adipose tissue, liver, and skeletal muscle under insulin resistance

Type 2 diabetes mellitus is the most common type of diabetes, and insulin resistance (IR) is its core pathological mechanism. Proteomics is an ingenious and promising Omics technology that can comprehensively describe the global protein expression profiling of body or specific tissue, and is widely applied to the study of molecular mechanisms of diseases. In this paper, we focused on insulin target organs: adipose tissue, liver, and skeletal muscle, and analyzed the different pathological processes of IR in these three tissues based on proteomics research. By literature studies, we proposed that the main pathological processes of IR among target organs were diverse, which showed unique characteristics and focuses. We further summarized the differential proteins in target organs which were verified to be related to IR, and discussed the proteins that may play key roles in the emphasized pathological processes, aiming at discovering potentially specific differential proteins of IR, and providing new ideas for pathological mechanism research of IR.

Postpartum assessment of the beta cell function and insulin resistance for Chinese women with previous gestational diabetes mellitus

Gestational diabetes mellitus (GDM) imparts a high risk of developing postpartum diabetes and is considered to be an early stage of type 2 diabetes mellitus (T2DM). In this study, a 75-g oral glucose tolerance test was performed on 472 women with GDM at 6-8 weeks after delivery. The clinical and metabolic characteristics were compared between the patients with normal glucose tolerance (NGT) and abnormal glucose metabolism (AGM). These data were then compared between pre-diabetic and diabetic patients. A total of 37.7% of the women with GDM continued to have abnormal glucose levels after delivery. Compared with the women who reverted to normal, HOMA-IR was significantly higher in AGM. A multiple stepwise regression analysis revealed that age, the postpartum body mass index (BMI), low density lipoprotein-cholesterol (LDL-C), 2 h glucose load plasma glucose (2 h PG), triglycerides (TG), hemoglobin A1c (HbA1c), 1 h glucose load plasma insulin (INS) level, and 2 h INS level were independent risk factors for the development of insulin resistance after delivery. This study has identified a high prevalence of AGM after GDM. Insulin resistance appears to be the major contributor. Any treatment to reduce the postpartum BMI and lipids level may be beneficial to decrease insulin resistance.

Comparison of serum concentrations of humanin in women with and without gestational diabetes mellitus

Humanin (MT-RNR2) is an endogenous polypeptide that is involved in many diseases, including T2DM. Gestational diabetes mellitus (GDM) is defined as hyperglycemia during pregnancy. The aim of this study was to evaluate serum humanin levels in women with or without GDM and to elucidate possible correlations with anthropometric parameters, metabolic parameters and the incidence of GDM. Eighty-four women with GDM and 73 control women were enrolled in this study. The clinical and biochemical parameters of all subjects were determined. Serum humanin levels were measured by an ELISA. Serum humanin levels were significantly lower in women with GDM than in control women. Moreover, humanin levels were significantly negatively correlated with the presence of GDM, body weight, BMI at 24 weeks of gestation, TG, FPG, 1 hPG, 2 hPG, FINS, and HOMA-IR. In contrast, humanin levels were significantly positively correlated with FT3 and FT4. A binary logistic analysis showed that humanin levels were associated with the incidence of GDM. Additional follow-up studies are needed to highlight whether and how decreased humanin levels play an important role in GDM.

Comparing twice- versus four-times daily insulin in mothers with gestational diabetes in Pakistan and its implications

BACKGROUND

Gestational diabetes mellitus is a common medical problem associated with maternal and fetal complications. Good glycemic control is the cornerstone of treatment.

OBJECTIVE

Compare outcomes between four times (q.i.d) and twice daily (b.i.d) regimens. The morning dose of the b.i.d regimen contained two-thirds of the total insulin, comprising a third human regular insulin and two-thirds human intermediate insulin; equal amounts in the evening.

METHODS

480 women at >30 weeks with gestational diabetes mellitus with failure to control blood glucose were randomly assigned to either regimen.

RESULTS

Mean time to the control of blood glucose was significantly less and glycemic control significantly increased with the q.i.d regimen. Operative deliveries, extent of neonatal hypoglycemia, babies with low Agpar scores and those with hyperbilirubinemia were significantly higher with the b.i.d daily regimen.

CONCLUSION

The q.i.d daily regime was associated with improved fetal and maternal outcomes. Consequently should increasingly be used in Pakistan, assisted by lower acquisition costs.

Identification of a Novel Function of Adipocyte Plasma Membrane-Associated Protein (APMAP) in Gestational Diabetes Mellitus by Proteomic Analysis of Omental Adipose Tissue

Gestational diabetes mellitus (GDM) is considered as an early stage of type 2 diabetes mellitus. In this study, we compared demographic and clinical data between six GDM subjects and six normal glucose tolerance (NGT; healthy controls) subjects and found that homeostasis model of assessment for insulin resistance index (HOMA-IR) increased in GDM. Many previous studies demonstrated that omental adipose tissue dysfunction could induce insulin resistance. Thus, to investigate the cause of insulin resistance in GDM, we used label-free proteomics to identify differentially expressed proteins in omental adipose tissues from GDM and NGT subjects (data are available via ProteomeXchange with identifier PXD003095). A total of 3528 proteins were identified, including 66 significantly changed proteins. Adipocyte plasma membrane-associated protein (APMAP, a.k.a. C20orf3), one of the differentially expressed proteins, was down-regulated in GDM omental adipose tissues. Furthermore, mature 3T3-L1 adipocytes were used to simulate omental adipocytes. The inhibition of APMAP expression by RNAi impaired insulin signaling and activated NFκB signaling in these adipocytes. Our study revealed that the down-regulation of APMAP in omental adipose tissue may play an important role in insulin resistance in the pathophysiology of GDM.

Preserved structural and functional characteristics of common carotid artery in properly treated normoglycemic women with gestational diabetes mellitus

Women with gestational diabetes mellitus (GDM) are at high risk of subsequently developing type 2 diabetes mellitus which is an important cardiovascular risk factor. We have evaluated whether preclinical morphological and functional arterial changes are present in GDM. Diameter, intima-media thickness (IMT), intima-media cross-section area (IMCSA) and elasticity features (compliance, distensibility coefficient, circumferential strain, stiffness index (SI) α and β, incremental elastic modulus) of the common carotid arteries (CCA) were studied in the 3rd trimester in 25 women with GDM, and 17 normal pregnant women matched for age and body mass index using an ultrasonographic vessel wall-movement tracking system and applanation tonometry. Mean IMT, IMCSA and SI α tended to be larger, whereas compliance was smaller in women with GDM but none of these differences were significant. Serum glucose (4.99 ± 0.51 vs. 4.79 ± 0.61 mmol/L, p=0.37) and HbA1c (5.33 ± 0.27 vs. 5.36 ± 0.47 mmol/L, p=0.85) proved normoglycemia in both groups. In conclusion, by the combination of methods we applied in this case control study, neither morphological nor functional characteristics of large elastic arteries differ significantly between well-treated normoglycemic women with GDM and non-diabetic pregnant women in the 3rd trimester.

Gestational Diabetes: A Review of the Current Literature and Guidelines

Despite large numbers of original research studies spanning 4 decades there is still no consensus on the subject of gestational diabetes. Should all pregnant women be screened or only those with risk factors? Or is it safe not to screen at all? Which screening test and which diagnostic test are the most reliable? Which cutoff values should we use? What are the risks involved for mother and baby and can treatment improve outcome? What is the connection between gestational diabetes and diabetes mellitus type II? Are there disadvantages to screening? A review of relevant articles shows that definitive answers to these questions are not yet available. There is no gold standard screening test and no threshold glucose value above which complications are markedly increased. On the contrary, there appears to be a continuum of slowly increasing risks with rising blood glucose values, where it seems difficult to draw a clear line between pathology and physiology. Moreover, treatment has thus far not been shown to significantly improve outcome. There seems to be an indistinct area between the diagnosis of gestational diabetes and diabetes mellitus type II, where women with risk factors for one are also predisposed to develop the other, thereby confusing the diagnosis. Finally, the disadvantages to diagnosing and treating women without a clearly proven benefit seem to be significant. Therefore it seems defensible to suspend all screening and treatment for gestational diabetes, or at least significantly raise the threshold for making a positive diagnosis and initiating treatment, until further research has proven a clear benefit.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to summarize that there is still no worldwide consensus on the diagnosis, management, and adverse effects of Gestational Diabetes Mellitus (GDM); explain that all methods of screening vary in sensitivity and depend on very strict preparations for screening; state that there is no agreement on ideal levels of blood glucose to prevent untoward effects; and recall that there are two very large prospective studies that clarify the dark waters and that we should await their results.

A population-based screening for gestational diabetes mellitus in non-diabetic women in Bahrain

BACKGROUND

Maternal hyperglycemia is considered a risk factor for fetal morbidity. Since there is a high prevalence of diabetes mellitus among the population of Bahrain, we conducted a prospective population-based study of gestational diabetes mellitus (GDM) in non-diabetic pregnant women.

SUBJECTS AND METHODS

All non-diabetic pregnant women attending antenatal clinics during January 2001 to December 2002 (n=10,495) were screened for GDM during the 24th to 28th weeks of gestation. All positive subjects based on a 50-g glucose challenge test (GCT) were further evaluated by a diagnostic 75-g oral glucose tolerance test (OGTT). The birth weight of the child and post-delivery insulin resistance were monitored. The homeostasis model of insulin resistance (HOMA-IR) was used to assess insulin resistance.

RESULTS

Of 10,495 non-diabetic pregnant women screened, 32.8% (n=3443) had plasma glucose > or = 7.8 mmol/L (140 mg/dL) in the GCT. The 75-g OGTT found a prevalence of GDM of 13.5%. There were twice as many Bahrainis as expatriates. Of children born to women with GDM, 6.5% had a birth weight > 4000 g. Post-delivery evaluation of insulin resistance indicated that 33% of women with GDM had a HOMA-IR value > 2.

CONCLUSION

The population of Bahrain is a high-risk ethnic group for GDM. The association of insulin resistance in the post-gravid state with GDM among 33% of the study population suggests that insulin resistance, the possible cause of the pathophysiological mechanism underlying the development of gestational diabetes, continues in the post gravid state.