Prandial Glycemia Research Articles

Inflammation and insulin resistance.

This Is the second of two articles describing a symposium on the relationship between inflammation and insulin resistance that was held in Niagra Falls, NY, 20–21 September 2002. Antonio Ceriello (Udine, Italy) discussed the role of glucose intake and postprandial hyperglycemia in the development of diabetes complications, as well as the relationship of hyperglycemia to oxidative stress. The DECODE (Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe) study showed high 2-h postload glucose to be associated with increased mortality independent of fasting glucose (1), and the Pacific and Indian Ocean Study showed isolated 2-h hyperglycemia to double the risk of mortality (2). The Funagata Diabetes Study showed that impaired glucose tolerance (IGT) but not impaired fasting glucose was a risk factor for cardiovascular disease (CVD) (3). There is evidence that lowering postprandial glucose improves outcome. Post hoc analysis of the STOP-type 2 diabetes study showed that myocardial infarction and hypertension decrease with use of the prandial glucose-lowering agent acarbose (4). In the Kumamoto study, postprandial hyperglycemia strongly predicted retinopathy and nephropathy (5). Endothelial dysfunction (ED) is a potential mediator of the effect of prandial glycemia, with altered vasodilation and procoagulant abnormalities. ED can be induced by hyperglycemia following a 75-g oral glucose load in persons with normal or IGT or with diabetes, with reduction of flow-mediated brachial artery dilation proportional to the degree of hyperglycemia (6). In a study of 225 persons with hypertension followed for 32 months, forearm ED was a marker of future CVD events (7), with a 4.5-year follow-up of 281 persons showing both ED and measures of oxidative stress to predict CVD events (8). Acute hyperglycemia may suppress vasodilation, which may involve oxidant stress, as it is reversed with antioxidant or l-arginine treatment (9). Glucose increases endothelial cell free radical production leading …

Inflammation and insulin resistance.

This Is the second of two articles describing a symposium on the relationship between inflammation and insulin resistance that was held in Niagra Falls, NY, 20–21 September 2002. Antonio Ceriello (Udine, Italy) discussed the role of glucose intake and postprandial hyperglycemia in the development of diabetes complications, as well as the relationship of hyperglycemia to oxidative stress. The DECODE (Diabetes Epidemiology: Collaborative analysis Of Diagnostic criteria in Europe) study showed high 2-h postload glucose to be associated with increased mortality independent of fasting glucose (1), and the Pacific and Indian Ocean Study showed isolated 2-h hyperglycemia to double the risk of mortality (2). The Funagata Diabetes Study showed that impaired glucose tolerance (IGT) but not impaired fasting glucose was a risk factor for cardiovascular disease (CVD) (3). There is evidence that lowering postprandial glucose improves outcome. Post hoc analysis of the STOP-type 2 diabetes study showed that myocardial infarction and hypertension decrease with use of the prandial glucose-lowering agent acarbose (4). In the Kumamoto study, postprandial hyperglycemia strongly predicted retinopathy and nephropathy (5). Endothelial dysfunction (ED) is a potential mediator of the effect of prandial glycemia, with altered vasodilation and procoagulant abnormalities. ED can be induced by hyperglycemia following a 75-g oral glucose load in persons with normal or IGT or with diabetes, with reduction of flow-mediated brachial artery dilation proportional to the degree of hyperglycemia (6). In a study of 225 persons with hypertension followed for 32 months, forearm ED was a marker of future CVD events (7), with a 4.5-year follow-up of 281 persons showing both ED and measures of oxidative stress to predict CVD events (8). Acute hyperglycemia may suppress vasodilation, which may involve oxidant stress, as it is reversed with antioxidant or l-arginine treatment (9). Glucose increases endothelial cell free radical production leading …

Cytochrome P450 2E1 activity in diabetic and obese patients as assessed by chlorzoxazone hydroxylation.

Cytochrome P450 2E1 (CYP2E1) is a phase I detoxification enzyme, which is induced by chronic alcohol consumption. It is involved in the activation of numerous carcinogens and in the production of free radicals. As it has previously been shown to be induced in diabetic and obese rats, the aim of this study was to investigate its induction level in poorly-controlled diabetics and in obese patients (Body Mass Index > 30 kg/m2). CYP2E1 activity was determined in 35 diabetic and 17 obese patients by using the in vivo chlorzoxazone hydroxylation test. Even though the glucidic parameters were highly disturbed (mean fasting glycemia > 7.9 mmol/L, post prandial glycemia > 12.2 mmol/L and fructosamine > 326 mumol/L), CYP2E1 activity was not enhanced either in insulin-dependent diabetics (IDDs, n = 7) nor in non-obese non-insulin-dependent diabetics (NIDDs, n = 15) when compared to controls (n = 42) (0.21 +/- 0.03, 0.33 +/- 0.03 and 0.30 +/- 0.02, respectively, mean +/- SEM). However, this activity was lower in IDDs when compared to NIDDs (P < 0.05). In obese patients, with (n = 13) or without (n = 17) NIDD mellitus, CYP2E1 activity was increased by a mean of 40% when compared to controls. In addition, positive correlations were found in all subjects (controls or patients, n = 74) between CYP2E1 activity and serum cholesterol (r = 0.42, P < 0.0001), triglycerides (r = 0.44, P < 0.0001) and BMI (r = 0.36, P < 0.001). Accordingly, subjects with cholesterol and/or triglyceride serum levels above 6.4 and 1.8 mmol/L, respectively, displayed a mean increase of 40% of their CYP2E1 activity vs subjects within the above values. It is believed that individuals with increased CYP2E1 activity are more susceptible to the adverse effects of CYP2E1-mediated activation of toxins and carcinogens.

Effect of vegetable fibre on post prandial glycemia

Effects of feeding different levels of vegetable fibre to normal and non-insulin dependent diabetics were studied. Influences of a control diet (diet with no vegetable fibre) and a purified fibre diet (Isapgol) were compared to results achieved with different levels of several vegetables. A negative correlation between the level of fibre and blood glucose levels in terms of mean percent peak rise, AUC, and per cent glycemic response was shown. Bitter gourd was more effective than the leafy vegetables. Even though the trend in post prandial glucose levels was same for both normal and diabetic subjects, the metabolic response varied significantly between the two groups.

Insulin action and determinants of glycaemia in a rat model of type 2 (non-insulin-dependent) diabetes mellitus.

We aimed to assess prandial responses, basal glucose turnover and insulin action (euglycaemic clamp) in a very low-dose neonatal streptozotocin model of Type 2 (non-insulin-dependent) diabetes mellitus. Male Wistar rats were injected at 2 days of age with 45 mg/kg streptozotocin or vehicle (control). At 8 weeks, the groups were subdivided and fed either a high-fat or high-starch diet for 3 weeks. Both the fat diet and streptozotocin treatments had independent hyperglycaemic effects (streptozotocin/fat 9.3 +/- 0.3 mmol/l; streptozotocin/starch 7.5 +/- 0.3 mmol/l; control/fat 7.4 +/- 0.1 mmol/l; all p less than 0.01 vs control/starch 6.4 +/- 0.1 mmol/l). The fat diet effect was associated with both a reduction in basal glucose clearance (p less than 0.001) and in basal hepatic glucose output (p less than 0.05). Streptozotocin increased basal hepatic glucose output. Significantly higher prandial glycaemia in the streptozotocin/starch group occurred despite similar insulin levels and appeared to be related to an impaired early insulin response. Whole-body and tissue-specific insulin sensitivity were significantly depressed in fat-fed animals compared to starch-fed animals, however there were no significant effects of streptozotocin treatment. We conclude that fasting hyperglycaemia associated with abnormalities in both glucose production and clearance can exist in the presence of a basal hepatic glucose output which is reduced compared to control animals. Furthermore, dietary-fat-induced insulin resistance is not exacerbated by the relative insulin deficiency and/or mild hyperglycaemia observed when dietary fat and neonatal streptozotocin-treatments are combined.

Fasting Plus Prandial Insulin Supplements Improve Insulin Secretory Ability in NIDDM Subjects

To examine how insulin secretory ability is modified by strict glycemic control in non-insulin-dependent diabetes mellitus (NIDDM) subjects, basal and/or prandial insulin was supplemented for 4 wk in 24 diabetic subjects who were secondary failures to sulfonylurea treatment. One intermediate-acting insulin injection a day (n = 7) failed to suppress the rise in plasma C-peptide after meals and did not improve plasma C-peptide responses during a posttreatment oral glucose challenge. Continuous subcutaneous insulin infusion with a premeal bolus (n = 8) suppressed both fasting and meal-related rises in C-peptide and improved C-peptide response during the posttreatment oral glucose challenge. Daily insulin requirements during the 4 wk of treatment were reduced significantly by 52%. A short-acting insulin injection before each meal (n = 9) without basal supplementation suppressed the prandial rise in C-peptide and was associated with a significant reduction in daily insulin requirements during 4 wk of treatment by 28%. Diabetic subjects whose fasting and prandial hyperglycemia were less than 140 and less than 200 mg/dl, respectively, showed a significantly higher C-peptide response during oral glucose challenge after treatment than those whose insulin treatment only normalized (less than 200 mg/dl) prandial but not basal hyperglycemia (greater than 140 mg/dl). These results suggest that a short-term period of meal-related insulin treatment (which normalized prandial glycemia) increases residual beta-cell function in NIDDM subjects who failed long-term sulfonylurea administration. A basal insulin supplement alone was not effective. The effectiveness of a prandial insulin supplement may have been further improved by a combined basal and meal-related treatment program.

Effects of the glycaemic index of dietary carbohydrates on prandial glycaemia and insulin therapy in type I diabetes mellitus

Four carbohydrate diets with different glycaemic index were fed to 10 type I diabetic patients on continuous subcutaneous insulin infusion (CSII). Every diet consisted of 4 meals with identical carbohydrate content, being consumed during one day each at 8.00, 12.00, 16.00 and 18.00 h. CSII was conducted according to the patients' experiences, aiming at plasma glucose values between 70 and 160 mg/dl. From 8.00 to 20.00 h, plasma glucose was measured every 2 h. Plasma glucose profiles were near-normal with all of the diets; differences between the diets were statistically insignificant. The premeal insulin dosages, as delivered by the patients, varied significantly in relation to the time of the day, and to the premeal plasma glucose concentration. The patients varied their prandial insulin doses also in relation to the 4 diets, indicating that the glycaemic index was helpful for the prediction of their prandial insulin requirements. It is concluded that near-normoglycaemia can be achieved in type I diabetic subjects on CSII irrespective of the glycaemic index of their diet, if the prandial insulin requirements are met adequately.

Cephalic phase of insulin secretion and food stimulation in humans: a new perspective.

Insulinemia and glycemia were measured at a 1-min interval at the hour of a lunch meal in human subjects. When no food was presented to naive subjects (n = 4), cyclic oscillations of insulinemia were found (period, 12-20 min; amplitude, 2.8-10.3 microU/ml). It is proposed that these spontaneous oscillations must be taken into consideration when evaluating the insulin response on cephalic contact with food stimuli; they might otherwise constitute a source of artifacts. Four subjects were then submitted to a series of four test meals scheduled at a 1-wk interval. Although their prandial glycemia remained comparable with preprandial values for the first 16 min of the meals, insulinemia often exhibited early peaks (within a few min after meal onset) whose amplitude appeared related to palatability conditions. Evidence suggests that the insulin peaks triggered by cephalic stimulation are Pavlovian reflexes that become conditioned to the test situation. A typical neuroendocrine response to alimentary frustration is also described. The results are discussed in perspective with animal works, in terms of the effects of neuroendocrine events on feeding behavior.

ESTUDOS SÔBRE AS PROVAS DE TOLERÂNCIA A GLICOSE POTENCIALIZADAS EM RECLUSOS DA PENITENCIARIA DO ESTADO DE SÃO PAULO. I - Prevalência do Diabetes Melito

The present paper is a preliminary phase of a study on the cortisone-glucose tolerance test. Diabetes prevalence in prisoners of the São Paulo State Penitenciary (Brazil) is studied using post prandial glycemia as a screening test and glucose tolerance test to confirm results on those who screened positive.