Interesting insulin response to oral glucose load in young Japanese subjects with impaired glucose tolerance

Ingestion of an exogenous ketone monoester improves the glycemic response during oral glucose tolerance test in individuals with impaired glucose tolerance: A cross-over randomized trial

AIMS/INTRODUCTION

As a low-carbohydrate diet and the use of sodium-glucose transporter-2 inhibitors are both known to increase D-beta-hydroxybutyrate levels, the effect of these levels on glucose metabolism has attracted attention. We investigated the acute effects of ketone monoester (KM) ingestion on blood glucose levels during the 75-g oral glucose tolerance test (OGTT) in participants with impaired glucose tolerance.

MATERIALS AND METHODS

Nine Japanese adults aged 48-62 years (4 men, 5 women) with impaired glucose tolerance participated in this study. After participants fasted overnight, we carried out OGTT for 180 min with and without KM ingestion on two separate days in a randomized cross-over design. We compared the area under the curve (AUC) of D-beta-hydroxybutyrate, glucose, insulin, C-peptide, glucagon and free fatty acids during OGTT.

RESULTS

The AUC of D-beta-hydroxybutyrate during OGTT was significantly higher with KM than without KM (KM 5995.3 ± 1257.1 mmol/L·h; without KM 116.1 ± 33.9 mmol/L·h, P < 0.0001), and the AUC of glucose with KM was significantly lower than that without KM (KM 406.6 ± 70.6 mg/dL·h; without KM 483.2 ± 74.3 mg/dL·h, P < 0.0001). This improved glucose excursion was associated with enhanced AUC of insulin during the first half (0-90 min) of OGTT, even though the AUC of C-peptide during this period was unchanged. In contrast, the AUC of insulin, C-peptide, glucagon and free fatty acids during 180 min of OGTT were similar in both conditions.

CONCLUSION

The ingestion of KM decreased the AUC of glucose during 75-g OGTT in Japanese individuals with impaired glucose tolerance, and the mechanism might involve elevated levels of circulating early phase insulin.

An inverse U-shaped association of late and peak insulin levels during an oral glucose load with glucose intolerance in a Japanese population: a cross-sectional study

The current study investigated the association of post-load insulin levels with glucose tolerance in a Japanese population. A total of 1450 Japanese employees who underwent a 75-g oral glucose tolerance test (OGTT) were included. Glucose tolerance was assessed by 120-min glucose levels during a 75-g OGTT. A penalized cubic regression spline model analysis revealed that the 60- and 120-min insulin levels, but not 0- or 30-min insulin levels, had an inverse U-shaped relationship to the 120-min glucose level. Furthermore, peak insulin level followed an inverse U shape in relation to the 120-min glucose level, whereas the peak of insulin appeared at a later point in time as the 120-min glucose level increased. These associations were similarly observed in both obese and non-obese subgroups, although obesity was associated with higher insulin levels. Peak insulin levels also demonstrated an inverse U shape in association with 0-min glucose levels and indices of β cell function, assessed by the disposition index and the β-cell function index. In conclusion, peak insulin levels followed an inverse U shape in relation to glucose intolerance in a Japanese population, whereas the impairment of glucose tolerance was associated with a delay in the time to reach peak insulin levels.

Type 2 diabetes in East Asians: similarities and differences with populations in Europe and the United States

There is an epidemic of diabetes in Asia. Type 2 diabetes develops in East Asian patients at a lower mean body mass index (BMI) compared with those of European descent. At any given BMI, East Asians have a greater amount of body fat and a tendency to visceral adiposity. In Asian patients, diabetes develops at a younger age and is characterized by early β cell dysfunction in the setting of insulin resistance, with many requiring early insulin treatment. The increasing proportion of young-onset and childhood type 2 diabetes is posing a particular threat, with these patients being at increased risk of developing diabetic complications. East Asian patients with type 2 diabetes have a higher risk of developing renal complications than Europeans and, with regard to cardiovascular complications, a predisposition for developing strokes. In addition to cardiovascular-renal disease, cancer is emerging as the other main cause of mortality. While more research is needed to explain these interethnic differences, urgent and concerted actions are needed to raise awareness, facilitate early diagnosis, and encourage preventive strategies to combat these growing disease burdens.

Pancreatic beta cell function in lean and obese Japanese with various degrees of glucose tolerance

The aim of the current study was to investigate whether obese subjects have different insulin secretory capacity compared to lean subjects with the same glucose tolerance in a Japanese population. We included a total of 1749 Japanese employees who underwent 75-g oral glucose tolerance test (OGTT). The study population was divided into deciles of 120-min glucose levels and the indices of insulin secretion and insulin sensitivity in each decile were compared between the subjects with and without obesity (body mass index ≥ 25 kg/m2). The indices used in the current study were Matsuda index, insulinogenic index, and disposition index. Obese subjects had significantly lower values of Matsuda index and significantly higher value of insulinogenic index than non-obese subjects in every decile (all p < 0.05). On the other hand, disposition index was not significantly different between non-obese and obese subjects in any decile of 120-min glucose level (all p > 0.05). Similar findings were observed when the study population was classified by waist circumference. In conclusion, disposition index derived from the data of 75-g OGTT was similarly decreased in obese Japanese subjects compared to non-obese Japanese subjects with the same post-load glucose levels. Future studies will be needed to confirm whether the development of glucose intolerance in obese Japanese subjects is accompanied by the same degree of pancreatic beta cell dysfunction as non-obese Japanese subjects.

C-peptide response to glucagon challenge is correlated with improvement of early insulin secretion by liraglutide treatment

The amelioration of glucose tolerance by liraglutide was associated with a significant improvement of early insulin-response during OGTT. The serum C-peptide response to glucagon challenge strongly correlated with the improvement of the early insulin-response. The C-peptide response to glucagon challenge would be useful to predict therapeutic response to liraglutide.

Prevalence of Abnormal Glucose Metabolism and Insulin Resistance Among Subtypes of Ischemic Stroke in Japanese Patients

Background and Purpose— The purpose was to assess the prevalence of disorders of glucose metabolism and insulin resistance in Japanese ischemic stroke patients with no history of diabetes by performing 75-gram oral glucose tolerance test (OGTT).

Methods— We recruited 427 ischemic stroke patients (atherothrombotic infarction, n=220; lacunar infarction, n=125; cardioembolic infarction, n=82). OGTT was used to evaluate disorders of glucose metabolism in stroke patients without previously known diabetes (n=113). We investigated the relationships among the prevalence of abnormal glucose metabolism, ischemic stroke subtypes, and the prevalence of insulin resistance using homeostasis model assessment for insulin resistance and immunoreactive insulin at 120 minutes after glucose loading (IRI 120 ).

Results— OGTT identified the presence of disorders of glucose metabolism in 62.8% of ischemic stroke patients without previously known diabetes, including diabetes (24.8%) and impaired glucose tolerance (lone impaired glucose tolerance and impaired fasting glucose plus impaired glucose tolerance, 34.5%). The prevalence of newly diagnosed diabetes and impaired glucose tolerance was the highest in the atherothrombotic infarction group (68.9%). The highest values of homeostasis model assessment for insulin resistance and immunoreactive insulin at 120 minutes after glucose loading were found in atherothrombotic infarction patients with abnormal glucose tolerance.

Conclusions— In this study, a significantly large percentage of Japanese patients with ischemic stroke and no history of diabetes were found to have disorders of glucose metabolism by OGTT. Impaired glucose tolerance and insulin resistance could play an important pathogenic role in the development of atherothrombotic infarction.

Japanese IGT subjects with high insulin response are far more frequently associated with the metabolic syndrome than those with low insulin response

Impaired glucose tolerance (IGT) represents a prediabetic state positioned somewhere between normal glucose tolerance and diabetes, which is also assumed to make individuals in this state highly susceptible to atherosclerotic disease. IGT also accounts for a highly heterogeneous population, with the condition varying from individual to individual. In this study, we stratified subjects with IGT by their insulin response and compare the pathology of IGT when it is associated with high or low insulin response to gain insight into the diverse pathology of IGT. Of the male corporate employees who underwent 75 g OGTT at the corporation's healthcare center, 150 individuals diagnosed with IGT (isolated IGT, combined IGT and IFG) comprised our study subjects. The study subjects were stratified into four quartiles by percentile AUC for insulin, and those in the 25th or less percentile were defined as the low insulin response group (n = 37), vs those in the 76th or greater percentile defined as the high insulin response group (n = 38), and these groups were compared. There was no significant difference observed between the two groups in regard to post-OGTT glucose response and area under the glucose curve. However, the high insulin response group was associated with higher BMI, subcutanesous fat area, uric acid levels, HOMA-beta cell values, and delta insulin/delta glucose (30 min) than the low insulin response group. The number of risk factors for the metabolic syndrome detected (as defined by the ATPIII diagnostic criteria) per subject was 2.84 +/- 0.17 and 2.08 +/- 0.20, respectively, in the high insulin response group and in the low insulin response group, with the number significantly (p < 0.05) higher in the high insulin response group. Furthermore, the incidence of the metabolic syndrome as defined by the ATPIII diagnostic criteria was 63.2% (24/38) in the high insulin response group vs 32.4% (12/27) in the low insulin response group, with the incidence significantly (p < 0.01) higher in the high insulin response group. Likewise, the incidence of the metabolic syndrome as defined by the Japanese diagnostic criteria was found to be significantly (p < 0.05) higher in the high insulin response group at 50% (19/38) compared to 27.0% (10/37) in the low insulin response group. Our study findings suggest that IGT subjects with high insulin response and those with low insulin response vary greatly in regard to the number of atherosclerotic risk factors complicated and the frequency with which they are associated with the metabolic syndrome. It is also shown in middle-aged Japanese males that of the two forms of IGT, IGT with high insulin response is more closely linked to the pathogenesis of atherosclerotic cardiovascular disease.

Effects of diet and/or exercise on the adipocytokine and inflammatory cytokine levels of postmenopausal women with type 2 diabetes

This study examined the independent and combined effects of diet and exercise on adipocytokine and inflammatory cytokines in postmenopausal women with type 2 diabetes. Using a randomized, controlled design, 33 women (age, 50-70 years) were assigned to diet alone (D), exercise alone (EX), or diet + exercise (D + E) for 14 weeks. Before and after the interventions, blood samples for adipocytokines and inflammatory markers were drawn, a meal test was performed, and abdominal fat distribution was measured by magnetic resonance imaging (MRI). Body weight decreased approximately 4.5 +/- 0.6 kg ( P < .05) after the D and D + E interventions, whereas only small changes in body weight were found with the exercise-alone intervention. Plasma C-reactive protein levels were decreased by approximately 15% with all 3 interventions, whereas leptin levels were reduced with the D and D + E intervention (D: pre = 48.7 +/- 6.0, post = 38.9 +/- 5.0 ng/mL; D + E: pre = 38.5 +/- 6.0, post = 22.9 +/- 5.0 ng/mL; P < .05) with no differences between groups. There was a trend for leptin levels to decrease in the EX group ( P = .06). Plasma resistin levels were not altered by the 3 interventions from pre- to posttreatment (D: pre = 6.9 +/- 0.6, post = 6.2 +/- 0.4 ng/mL; D + E: pre = 5.6 +/- 0.6, post = 5.7 +/- 0.4 ng/mL; E: pre = 6.2 +/- 0.6, post = 5.9 +/- 0.6 ng/mL, P > .05), and no differences in adiponectin and tumor necrosis factor alpha (TNF- alpha ) levels were found. Visceral adipose tissue and tumor necrosis factor alpha were the only predictors of calculated insulin resistance ( P < .05), explaining 43% of the variability. A typically prescribed weight loss program with lifestyle changes resulted in few changes in adipocytokines and inflammatory cytokines in older women with type 2 diabetes, suggesting that dramatic weight loss or clinical interventions are needed.

Diabetes trends in Japan

The prevalence of diabetes is increasing in Japan, and it is estimated that more than 12 million Japanese people are hyperglycemic. This high prevalence is most likely the result of a complex interplay between genetic and environmental factors specific to Japan. The lifestyle and diet of the Japanese population have changed significantly since the end of World War II. In general, the Japanese have become more sedentary and they consume more fat than in the past. Among Japanese men, these changes have been associated with a steadily increasing body mass index (BMI), a well-known risk factor for the development of insulin resistance, impaired glucose tolerance, and diabetes. Genetic characteristics common to many Japanese may also contribute to their higher prevalence of diabetes. The Japanese have a higher prevalence of polymorphisms for at least three genes that code for proteins thought to play key roles in lipid and glucose metabolism: the beta 3-adrenergic receptor, the peroxisome proliferator-activated receptor gamma, and calpain-10. The interaction between changes in lifestyle and the 'thrifty' genotype characteristic of many Japanese people may play a significant role in the increasing prevalence of diabetes and associated cardiovascular risk in this population.