Gut microbiota plays a major role in the process of food absorption and low grade inflammation, two key steps in obesity and diabetes mellitus occurrence. Gut microbiota metabolites, such as short chain fatty acids (SCFA), have an important impact over the metabolic pathways like insulin signalling, incretin production and inflammation. [1-3] We aimed to study the microbiota patterns in obese and T2D patients from Black Sea Coast region, considering the ethnic mixture, environmental and geographical particularities, involving diet or various habits in this area. 100 patients and 100 controls matched by age, gender and ethnicity were studied regarding feaces predominance of Lactobacillus and Bifidobacterium species. We compared the results of microbiota patterns from patients to those obtained in a similar control group of healthy subjects. The standard pour plate 0.05% L-cystine enriched method was used to obtain the bacterial cultures and anaerobic conditions. Morphological and biochemical tests were used to identify the Lactobacillus and Bifidobacterium spp. Fecal organic acid concentrations were explored in frozen samples. The association between bacterial counts/organic acid concentrations and independent variables, including age, diet, ethnicity and other risk factors were calculated using multivariable linear regression analysis. Pearson�s correlation coefficients were calculated to detect associations between fecal bacteria counts/organic acid concentrations and laboratory variables (serum biomarkers, body mass index, age, and severity of obesity/T2D according to international scales). Junk and sweet diets, lack of physical activity and familial aggregation of hypercholesterolemia and diabetes were significantly more often present in our T2D/obese patients than in controls. The bacterial counts of the L. acidophilus, L plantarum and L. reuteri subgroups of Lactobacillus sp were significantly lower among patients with T2D and obesity than in controls. The counting of Bifidobacterium spp revealed a higher presence of B. bifidum in controls than in obese or T2D patients. Diet type (junk food and sweets), BMI (]25) and personal history of metabolic disorders were associated with decreased counts of L acidophilus and increased counts of L. fermentum and B. adolescentis in T2D patients. Ethnicity, metabolic disorders history and junk and sweet diet were associated with low counts of L. acidophilus and L. reuteri and low counts of B. longum. Junk and sweet diet was associated with low counts of B. bifidum. Romanian ethnicity and metabolic disorders were associated with low counts of B. choerinum at obese patients, independent of age or previous antidiabetic treatments. The concentrations of acetic and butyric acids were significantly lower in all patients groups, while the concentrations of valeric acid were significantly higher in patients with untreated T2D and obese patients compared to the controls. Low counts of L. acidophilus and L. reuteri were positively correlated with the increased levels of HbA1c, LDL cholesterol, TG and inflammatory markers such as CRP, ESR and IL-6, no matter of diet, age, ethnicity or metabolic disorders history. Also, low counts of B. bifidum and B. infantis were positively correlated with high levels of CRP, IL-6 and TG. In obese patients, statistic analysis results showed that low counts of L. acidophilus, L. plantarum, L. johnsonii and L. reuteri were positively associated with increased levels of CPR, IL-6 and TG, while low counts of B. bifidum, B infantis and B. breve were positively correlated with higher counts of CPR, LDL cholesterol and TG. Low counts of B. bifidum and B choerinum were positively correlated with low counts of HDL cholesterol in Romanian ethnicity patients and in those with previous metabolic disorders. Low bacterial counts of some particular strains of Lactobacillus spp and Bifidobacterium spp were positively correlated with diet type, BMI, Romanian ethnicity and personal history of metabolic disorders obese and T2D patients from Romanian Black Sea Coast Region.