Dichotomous responses of inter and postprandial hyperglycaemia to short-term calorie restriction in patients with type 2 diabetes

Combined Effects of a Dietary Fiber Mixture and Wheat Albumin in a Rat Model of Type 2 Diabetes Mellitus

As bioactive ingredients of functional foods, dietary fiber and wheat albumin (WA) are known to suppress hyperglycemia in patients with type 2 diabetes mellitus. The combined effects of these bioactive ingredients were examined using an animal model of type 2 diabetes mellitus. First, oral starch tolerance tests (OSTTs) with the simultaneous intake of a dietary fiber mixture (DF) and WA were performed as an acute study. Male Goto-Kakizaki rats received a soluble starch solution [700 mg/kg body weight (bw)] containing DF and/or WA (each 300 mg/kg bw). In these OSTTs, the combined intake of DF and WA suppressed hyperglycemia much more effectively than each separate intake. Second, in a chronic intake study, diets containing DF and/or WA were administered to male Zucker diabetic fatty rats over 84 d. The combined effects of DF and WA were not observed in glycosylated hemoglobin concentration levels or fasting blood glucose levels, but appeared as an improvement in liver lipid contents. Variations in the liver lipid contents were similarly reflected in those of the plasma lipid concentrations. In conclusion, this study found that the simultaneous intake of bioactive DF and WA improved the postprandial hyperglycemia and the chronic lipid metabolism disorders in rat models of type 2 diabetes mellitus.

Exploring blood glucose variation over geographical space

BACKGROUND

Type 2 diabetes mellitus is known to be associated with environmental, behavioral, and lifestyle factors such as a sedentary lifestyle, overly rich nutrition, and obesity. However, the day-to-day human-environment interactions and real-life activities that cause an individual's blood glucose to fluctuate remain relatively unexplored, owing in part to data collection challenges. This article presents a novel data collection system that overcomes these challenges and allows exploration of the spatial correlates of blood glucose fluctuation.

METHODS

An automated monitoring system was developed combining a Global Positioning System (GPS) receiver with a continuous blood glucose monitor. The GPS was used to elicit a second-by-second accounting of an individual's daily activities alongside blood glucose measurement every 5 min. A pilot study of 40 diabetes patients was conducted over a 72-h period. Geographic Information System software was used to generate blood glucose maps, incorporating methods to deal with scale issues, overlapping data, and to protect subject identity.

RESULTS

Individual blood glucose variation maps revealed a variety of distinct patterns. Most subjects had at least two major anchor points in their life combined with a variety of other activity locations at varying distances from home, many associated with quite distinct low or high blood glucose values. Further statistical analysis revealed location and distance from home were significantly correlated with blood glucose variation-although the strength and direction of the effect was quite mixed.

CONCLUSIONS

Results suggests that blood glucose and space/location are highly correlated and should be considered further as a lifestyle-related risk factor for diabetes patients. In the future, patients and caregivers may benefit from individualized visualization tools that help identify problematic locations that require special attention.

Continuous glucose monitoring in non-insulin-using individuals with type 2 diabetes: acceptability, feasibility, and teaching opportunities

BACKGROUND

Continuous glucose monitoring (CGM) has the potential to provide useful data for behavioral interventions targeting non-insulin-using, sedentary individuals with type 2 diabetes mellitus (T2DM). The aims of this study were to describe CGM in terms of (1) feasibility and acceptability and (2) dietary- and exercise-teaching events.

METHODS

Cross-sectional data were analyzed from 27 non-insulin-using adults with T2DM who wore CGM for 72 h as part of a larger study on using CGM for exercise counseling in this population. Feasibility data included accuracy of entering daily self-monitored blood glucose (SMBG) readings and events (e.g., meals, exercise), sensor failures, alarms, optimal accuracy of glucose data, and download failures. Acceptability data included CGM satisfaction and wearing difficulties. Dietary- and exercise-teaching events were identified from CGM and activity monitor data.

RESULTS

CGM graphs showed 141 dietary- and 71 exercise-teaching events. About half the participants (52%) reported difficulty remembering to enter events into CGM monitors, but most (82%) kept an accurate paper log of events. Insufficient SMBG entries resulted in 32 CGM graphs with "use clinical judgment" warnings. Eighty-three percent of missed SMBG entries were from 18 participants 55-77 years old. Missing correlation coefficients resulted from glucose concentrations varying <100 mg/dL. A majority of participants (n = 19) were willing to wear CGM again despite reporting minor discomfort at sensor site and with wearing the monitor.

CONCLUSIONS

CGM data provided several teaching opportunities in non-insulin-using adults with T2DM. Overall, CGM was acceptable and feasible. Some identified problems may be eliminated by newer technology.

Optimizing diabetes management through glucose profiling: a case-based approach

It is well documented that tight glucose control prevents the microvascular complications of diabetes, and many studies suggest that postprandial hyperglycemia may be associated with macrovascular complications. Maintaining target glucose values is challenging, as therapies are often not targeted to individual glucose excursion patterns. Postprandial SMBG values may be more tightly correlated to HbA1c than are fasting values. Studies of patients with pregnancies complicated by diabetes demonstrate that using SMBG around meals significantly improves glucose control and pregnancy outcomes. Adopting this model in type 2 diabetes may help achieve better glycemic control.

Calibration of the continuous glucose monitoring system for transient glucose monitoring

BACKGROUND

Oral glucose tolerance testing (OGTT) remains the gold standard for diagnosis of diabetes and is used commonly in the research laboratory. The Medtronic MiniMed (North-ridge, CA) Continuous Glucose Monitoring System (CGMS Gold), developed for long-term monitoring of glycemic levels, could provide a convenient means for tracking OGTT results during research protocols; however, the sensor demonstrates glucose and time dependencies that preclude direct application of the company-provided conversion algorithm in the first 12-24 h after sensor insertion. Here, we propose an alternative conversion algorithm that permits utilization of the CGMS monitor for glucose monitoring during this time.

METHODS

Healthy female participants underwent CGMS monitoring during OGTT or fasting sessions in combination with finger-stick blood glucose measurements. Logarithmic transformations and multiple regression analysis were used to quantify the time and glucose dependence of the sensors.

RESULTS

Sensor performance, as characterized by sensitivity (ratio of sensor current to capillary blood glucose levels), was shown to vary logarithmically with glucose levels as well as time after sensor insertion. A conversion algorithm developed on the basis of these observations was tested on 17 subjects during OGTT. A mean absolute relative difference between capillary blood glucose and CGMS values of 11.6 +/- 6.5% for the new algorithm was seen, compared to 20.6 +/- 5.9% with the Medtronic Solutions version 3.0c algorithm.

CONCLUSIONS

Incorporation of the glucose and time dependence in CGMS sensor data yields an improved mean absolute difference between actual and estimated blood glucose values compared to the Medtronic-supplied algorithm in the immediate time period following sensor insertion.

Continuous glucose monitoring in patients with type 2 diabetes: Why? When? Whom?

The overall assessment of glycaemic control in patients with type 2 diabetes should normally include the monitoring of three parameters that are usually depicted as the 'glucose triad': HbA(1c), fasting plasma glucose (FPG) and postprandial glucose (PPG) excursions. However one additional marker, the so-called 'glucose variability' might be as important as the three others since it has been demonstrated that both upward and downward glucose fluctuations are potent activators of oxidative stress. Even though many methods have been proposed for assessing glucose fluctuations, the 'mean amplitude glucose excursions' (MAGE) index remains the 'gold standard'. However MAGE estimation requires the use of continuous glucose sensors. Despite the debate on the reliability and cost of the devices that permit glucose monitoring, we suggest that interventional trials designed to evaluate the effects of glucose fluctuations on diabetic complications should benefit from the use of continuous glucose monitoring systems (CGMSs). More prosaically, the use of these technologies could be extended to current clinical care of type 2 diabetic patients especially for motivating them to accept earlier insulin treatments in case of 'oral antidiabetic drug secondary failure', and further for choosing the most appropriate insulin regimen.

Is dietary restriction beneficial for human health, such as for immune function?

PURPOSE OF REVIEW

The impact of dietary restriction on physiologic function in humans is now beginning to be examined. The clinical trials are fueled by decades of animal experiments showing that dietary restriction delays the aging process and decreases the incidence of many age-associated diseases. The critical issue addressed in this article is whether or not dietary restriction long term is feasible or beneficial in humans.

RECENT FINDINGS

Short-term dietary restriction in humans does appear to have beneficial effects at lowering metabolism, especially when examining carbohydrates and weight loss. Dietary restriction long term does, however, have detrimental psychological effects in humans, making its feasibility questionable. Even short-term dietary restriction can negatively impact physical activity and potentially some aspects of immunity. The best avenue for humans to benefit from dietary restriction would be for pharmacological or bioactive food ingredient mimetics to be developed which would be more applicable for long-term use.

SUMMARY

Dietary restriction per se is unlikely to emerge as a feasible long-term strategy to improve human health. Developing dietary restriction mimetics targeting energy metabolism may prove beneficial, not only in aging, but also in diabetes and obesity.

Influence of acute exercise on hyperglycemia in insulin-treated type 2 diabetes

INTRODUCTION

The impact of exercise on blood glucose homeostasis has not been assessed in long-standing type 2 diabetes patients receiving exogenous insulin treatment.

PURPOSE

To study the effects of an acute bout of exercise on the subsequent 24-h blood glucose excursions under free-living conditions in insulin-treated type 2 diabetes patients.

METHODS

Eleven male type 2 diabetes patients (59 +/- 2 yr) performed an acute bout of exercise. One day before the exercise bout, a continuous glucose monitoring system (GlucoDay, A. Menarini Diagnostics) was inserted subcutaneously in the periumbilical region. The glucose sensor continuously measured glucose concentrations in the dialysate during a 48-h period.

RESULTS

The prevalence of hyperglycemic glucose excursions was reduced by 39% during a 24-h period (equivalent to 3 h) after an acute bout of exercise (P < 0.05). Average glucose concentrations 24 h before and after the exercise bout did not differ (NS). Mean dialysate glucose concentrations and the prevalence of hyperglycemic periods correlated strongly with baseline blood HbA1c concentrations (Pearson's R = 0.69, P < 0.05).

CONCLUSION

An acute bout of exercise effectively reduces the prevalence of hyperglycemia during a 24-h period under free-living conditions in long-standing type 2 diabetes patients on exogenous insulin therapy.

Monitoring Exercise-Induced Changes in Glycemic Control in Type 2 Diabetes

PURPOSE

The present study determined the efficacy of the Continuous Glucose Monitoring System (CGMS) during moderate exercise and monitored the changes in whole-day glucose profiles using the CGMS in individuals with and without type 2 diabetes.

METHODS

Six, obese, diet-treated individuals with and four age-matched individuals without type 2 diabetes were monitored using the CGMS for 3 d. Subjects cycled at 90% of a predetermined lactate threshold for 1 h at approximately 09:00 h on day 2, during which venous blood was sampled at 10-min intervals and immediately analyzed for glucose concentrations.

RESULTS

Venous blood glucose and CGMS values declined during exercise in the diabetes (P < 0.001) but not the control group (P = 0.085). The CGMS overestimated blood glucose in the control (P = 0.003) and the diabetes (P = 0.045) groups during exercise. The number of data points outside of the 95% confidence intervals was <5% in both groups, showing that there is a statistically acceptable level of agreement between venous blood glucose and CGMS values during exercise. Moderate exercise improved whole-day average glucose concentrations (P = 0.007) and whole-day area under the glucose curve (P = 0.016) values (AUCglu), and the time spent within +/-10% of fasting venous glucose (FVG) increased in the diabetes group (P = 0.021). No such effects were seen in the control group.

CONCLUSION

Using continuous glucose monitoring we were able to demonstrate that a period of moderate exercise improved whole-day glycemic control in obese individuals with type 2 diabetes. The CGMS should only be used as an adjunct and not as an alternative to frequent blood glucose sampling when examining the changes in glucose values during exercise in individuals with and without type 2 diabetes.