Effect on the postprandial glycaemic level of the addition of water to a meal ingested by healthy subjects and Type 2 (non-insulin-dependent) diabetic patients

Abstract

Summary. The effects on postprandial glycaemic reactions of adding a glass of water to a meal were studied in 7 healthy male subjects and 20 Type 2 (non-insulin-dependent) diabetic patients for a period of up to 3 h. The subjects were served a meal of potatoes and meat, with or without 300 ml of water, in random order on two mornings after a 12-h fast. The diabetic patients were considered as well-controlled or not well-controlled according to HbAlc and blood glucose fasting values. Water addition increased the peak blood glucose (p < 0.02) and serum insulin (p < 0.02) levels in healthy subjects, and the blood glucose concentration in well-controlled diabetic patients (p < 0.02). The addition of water also increased the overall blood glucose response, calculated as the positive incremental area, in healthy subjects by 68 + 25% (p < 0.02) and in well-controlled diabetic patients by 40 + 14% (p < 0.01). In poorly-controlled diabetic patients, however, the addition of water did not display significant effects, probably due to the varying fasting glycaemia in these patients. Thus, altering the physical property of a meal by dilution with water can affect the physiological responses; the results are considered to be relevant for the on-going discussion concerning the use of physiological responses to foods as a basis for diet instructions to diabetic patients.Key words: Type2 (non-insulin-dependent) diabetes, postprandial glycaemia, water ingestion, glycaemic index.Physiological responses to carbohydrate foods have been suggested as a basis for instructions to diabetic patients [1, 2] preferable to the traditional exchange system built on quantity and molecular weight of the carbohydrate content [3]. This is a conclusion from studies which have shown varying postprandial blood glucose responses after the ingestion of comparable and isocaloric food items. The blood glucose rise following the consumption of potatoes is higher than after the consumption of most other starchy foods [1,4,5]. Moreover, the plasma glucose response in healthy subjects is 40-60% lower when a monosaccharide or starch is served as a solid meal, than when the same carbohydrate is given as a liquid [6]. The physical property of starchy foods has also been shown to affect blood glucose and hormonal levels following meals [7,8].The identification of meal characteristics that attenuate the glycaemic response is far from complete. In many countries, it is common to drink during a meal, but knowledge of the effects of adding liquids to meals on the postprandial response is limited. It has been reported in abstracts that adding water to meals can increase the glycaemic response in healthy subjects [9,10]. The effect of drinking during meals on the glycaemic response in diabetic patients is, however, virtually unknown. The rate of gastric emptying affects the absorption rate of meal components and is related to the postprandial blood glucose level after meals [5,11,12]. Solid foods of meat, labelled by radioactive isotopes to measure gastric emptying, h...

Effect of Meal Dilution on the Postprandial Glycemic Response: Implications for glycemic testing

“…Torsdottir and Andersons (17) finding that the addition of 300 ml of water to a solid meal significantly increased the PGR, in both normal and well-controlled type 2 diabetic subjects, supports the findings of this study In contrast, their finding that the same addition of water had no significant effect on PGR in poorly controlled type 2 diabetic patients does not. The subsequent findings of Gregersen et al (24) are also at variance with the results of the present study.…”

“…The proposed mechanism for this observed effect of water on glycemia is thought to involve gastric emptying (17). Several studies have shown a relationship between gastric emptying and both water volume and osmolality in healthy subjects.…”

Glycaemic index methodology

“…Unfortunately, the results of studies undertaken to date to evaluate the effect of volume on glycaemic response are contradictory. Some authors found no significant effect of water volume (Gregersen et al 1990), whereas others observed or indicate a relationship between the volume of water or food and postprandial responses, and sometimes incremental areas (Torsdottir & Anderson, 1989;Young & Wolever, 1998;Sievenpiper et al 2001). These contradictory results could be explained by differences in physiology between diabetic and normal subjects and also by large variations between the protocols used in these studies.…”

Impact of Diet Composition on Blood Glucose Regulation

“…In poorly controlled diabetic subjects, however, no significant effect was found, probably due to the varying fasting glycemia in these subjects (Torsdottir and Andersson, 2009). In another study in T2DM subjects, similar glucose responses were found to test meals with either 90 or 600 mL of tap water (Gregersen et al, 1990).…”