We aim to present an overview of the possible influence of drinking water in general and mineral water in particular in improving glycemic parameters in persons with or without type 2 diabetes. We performed a literature search that produced 15 randomized controlled trials (RCTs) on this topic with mainly small sample sizes. We also discuss relevant observational and animal studies as well as the effects of important supplements in mineral water such as hydrogencarbonate and magnesium. There is low evidence for the positive effects of water or mineral water in improving glycemic parameters in diabetic and non-diabetic persons, and the results are heterogenous, making it difficult to reach an unequivocal conclusion. Meta-analyses of prospective cohort studies and other observational studies, studies with animal models and interventional studies using hydrogencarbonate and magnesium supplements suggest a probable positive effect of drinking water and mineral water in particular on glycemic parameters, supporting the positive results found in some of the RCTs, especially those substituting diet beverages or caloric beverages with water, or those using bicarbonate and magnesium-rich water. Regarding the high prevalence, the associated suffering and the resulting health expenditures of type 2 diabetes, it is imperative to conduct larger and more rigorous trials to answer the question whether drinking water or mineral water can improve glycemic parameters in diabetic and non-diabetic persons.People who don't drink sugar sweetened beverages tend to have higher quality diets and do not compensate for sugar or energy deficits by consuming more sugary foods [7].A nutrition survey examining the relationship between the quantity of water taken in and HbA1c in 1035 participants calculated that an increase of 240 mL in daily water intake reduces the risk of elevated HbAc1 >5.5% by 22% in men but not in women [8].A review of 134 randomized controlled trials (RCTs), where water consumption was increased right before or during a meal, showed heterogenic effects on energy intake, energy expenditure, fat oxidation and weight change [9].Moreover, mineral nutrients such as bicarbonate [10] and magnesium [11], in particular, are thought to affect glucose metabolism. An increased dietary acid load is associated with the development of insulin resistance [12], while a pre-existing diabetes favors acidosis, which, in turn, leads to increased insulin resistance [13].Drinking recommendations are less common and detailed than food recommendations [3,14], and there is little scientific evidence, and, to our knowledge, no review of RCTs on drinking water and its influence on glycemic parameters, respectively type 2 diabetes.This review aims to explore to what extent drinking water with low or high mineralization for at least four weeks influences glycemic parameters in healthy or type 2 diabetes participants in daily life situations as compared with other drinks. The results of the RCTs found in the literature search will be discussed alongsid...