Gut Microbiota Composition in Prediabetes and Newly Diagnosed Type 2 Diabetes: A Systematic Review of Observational Studies.

Evidence of gut microbiota involvement in regulating glucose metabolism and type 2 diabetes mellitus (T2DM) progression is accumulating. The understanding of microbial dysbiosis and specific alterations of gut microbiota composition that occur during the early stages of glucose intolerance, unperturbed by anti-diabetic medications, is especially essential. Hence, this systematic review was conducted to summarise the existing evidence related to microbiota composition and diversity in individuals with prediabetes (preDM) and individuals newly diagnosed with T2DM (newDM) in comparison to individuals with normal glucose tolerance (nonDM). A systematic search of the PubMed, MEDLINE and CINAHL databases were conducted from inception to February 2021 supplemented with manual searches of the list of references. The primary keywords of "type 2 diabetes", "prediabetes", "newly-diagnosed" and "gut microbiota" were used. Observational studies that conducted analysis of the gut microbiota of respondents with preDM and newDM were included. The quality of the studies was assessed using the modified Newcastle-Ottawa scale by independent reviewers. A total of 18 studies (5,489 participants) were included. Low gut microbial diversity was generally observed in preDM and newDM when compared to nonDM. Differences in gut microbiota composition between the disease groups and nonDM were inconsistent across the included studies. Four out of the 18 studies found increased abundance of phylum Firmicutes along with decreased abundance of Bacteroidetes in newDM. At the genus/species levels, decreased abundance of Faecalibacterium prausnitzii, Roseburia, Dialister, Flavonifractor, Alistipes, Haemophilus and Akkermansia muciniphila and increased abundance of Lactobacillus, Streptococcus, Escherichia, Veillonella and Collinsella were observed in the disease groups in at least two studies. Lactobacillus was also found to positively correlate with fasting plasma glucose (FPG), HbA1c and/or homeostatic assessment of insulin resistance (HOMA-IR) in four studies. This renders a need for further investigations on the species/strain-specific role of endogenously present Lactobacillus in glucose regulation mechanism and T2DM disease progression. Differences in dietary intake caused significant variation in specific bacterial abundances. More studies are needed to establish more consistent associations, between clinical biomarkers or dietary intake and specific gut bacterial composition in prediabetes and early T2DM.

A Case of Paraganglioma with Cyanotic Congenital Heart Disease.

Co-occurrence of cyanotic congenital heart disease (CCHD) and phaeochromocytoma (PCC) and paraganglioma (PGL) are rare, although some cases have been reported. We report a case of left paraganglioma in a 20-year-old lady with an underlying CCHD who underwent palliative Glenn shunt, subsequently developed polycythaemia and cavernous sinus thrombosis presented with palpitation, sweating, headache and hypertension of 3-months duration at the age of 17. The abdominal CT scan revealed an enhancing left paraaortic mass measuring 5.2 cm x 4.4 cm x 3.8 cm. A 24-hour urine catecholamine demonstrated raised noradrenaline level to six times upper limit of normal and hence diagnosis of left sympathetic (sPGL) was made. In view of the delayed diagnosis and significant morbidity associated with her condition, surgical treatment is no longer an option. Therefore, vigilant screening and early treatment of PCC-PGL in patients with CCHD are crucial in order to avoid significant morbidity and ensure a good quality of life.