Remnant-like particle cholesterol, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients

Factors responsible for deteriorating glucose tolerance in newly diagnosed type 2 diabetes in Japanese men

Hyperglycemia frequently continues to worsen even after the diagnosis of overt diabetes. The aim of this study is to evaluate the factors contributing to increasing glucose intolerance after onset of type 2 diabetes in Japanese subjects. Five hundred fifty newly diagnosed type 2 diabetic patients were classified into 3 degrees of hyperglycemia based on plasma glucose levels estimated by 75-g oral glucose tolerance test: diabetes mellitus with isolated fasting hyperglycemia (DM/IFH), DM with isolated postchallenge hyperglycemia (DM/IPH), and DM with fasting and postchallenge hyperglycemia (DM/FPH). In addition, the DM/IFH and DM/IPH groups were subdivided to clarify the determinants of fasting and postchallenge hyperglycemia. Insulin secretion was evaluated by insulinogenic index, and insulin sensitivity was evaluated by composite index of insulin sensitivity (ISI composite). The insulinogenic index in DM/IFH was highest of the 3 groups (P < .0001). The insulinogenic index in DM/IPH was higher than in DM/FPH (P < .0001). The international sensitivity index composite in DM/IPH was highest of the 3 groups (P < .05). Although impaired early-phase insulin secretion plays the crucial role in deterioration from DM/IFH to DM/FPH in Japanese subjects, impaired early-phase insulin secretion and decreased insulin sensitivity both are factors in deterioration from DM/IPH to DM/FPH. In addition, comparison of subgroups of DM/IFH and DM/IPH shows that although decreased early-phase insulin secretion plays the more significant role in postchallenge hyperglycemia in Japanese subjects, insulin sensitivity is the more important factor in fasting hyperglycemia.

High plasma level of remnant-like particle cholesterol in the metabolic syndrome

OBJECTIVE

The metabolic syndrome is associated with a high incidence of cardiovascular disease even when the abnormalities present in the syndrome are mild. The underlying mechanism of the metabolic syndrome has not been elucidated. We investigated whether a strong atherogenic lipoprotein, remnant-like particle (RLP) lipoprotein cholesterol, is elevated in the metabolic syndrome.

RESEARCH DESIGN AND METHODS

We performed a health examination among the residents of a rural community in Japan. Complete datasets, including fasting RLP cholesterol levels, were obtained in 1,261 subjects (509 men and 752 women) without diabetes and who were not taking lipid-lowering drugs. The subjects' medical history, use of alcohol, and smoking habits were ascertained by a questionnaire.

RESULTS

All of the components of the metabolic syndrome were significantly related to RLP cholesterol by univariate analysis. Total cholesterol and smoking habits were also positively associated with RLP cholesterol. The subjects with the metabolic syndrome showed only mild abnormalities of each component. When RLP cholesterol levels were stratified by the number of the components of the metabolic syndrome, there was a strong association between RLP cholesterol levels and the number of components (P < 0.001 and F = 72.7).

CONCLUSIONS

RLP cholesterol levels are elevated in the metabolic syndrome, and this elevation may underlie the high incidence of cardiovascular disease in the metabolic syndrome.

Three measures of tumor necrosis factor alpha activity and insulin resistance in nonobese Japanese type 2 diabetic patients

The aim of the present study was to investigate the relationship between insulin resistance and tumor necrosis factor alpha (TNF-alpha) as well as soluble TNF receptors (sTNF-R), body mass index (BMI), leptin, adiponectin, and serum lipid profile including triglycerides in nonobese Japanese patients with type 2 diabetes. A total of 88 nonobese Japanese type 2 diabetic patients were studied. The duration of diabetes was 11.0 +/- 0.8 years. In conjunction with BMI, glycosylated hemoglobin (HbA1c), fasting concentrations of plasma glucose, serum lipids (triglycerides, high-density lipoprotein cholesterol, and total cholesterol), serum leptin, serum adiponectin, serum TNF-alpha, and soluble TNF receptors (sTNF-R1 and sTNF-R2) were also measured. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment. Insulin resistance was positively correlated with BMI, triglycerides, leptin, and total cholesterol and negatively correlated with adiponectin and high-density lipoprotein cholesterol. In contrast, insulin resistance was not associated with TNF-alpha, nor sTNF-R (sTNF-R1 and sTNF-R2) in our diabetic patients. There was no significant relationship between the 3 measures of TNF-alpha system (TNF-alpha, sTNF-R1, and sTNF-R2) and BMI, serum triglycerides, leptin, or adiponectin in these patients. From these results, it can be concluded that peripheral levels of TNF-alpha system activity are not a major factor responsible for insulin resistance in nonobese Japanese type 2 diabetic patients.

Insulin secretion and insulin sensitivity in Japanese subjects with impaired fasting glucose and isolated fasting hyperglycemia

Impaired fasting glucose (IFG) is a subgroup of impaired glucose regulation exhibiting an elevated fasting glucose levels without elevated 2-h glucose levels on oral glucose tolerance test (OGTT). Diabetes mellitus with isolated fasting hyperglycemia (DM/IFH) is a similar subgroup of diabetes having higher fasting glucose levels with 2-h glucose levels within the non-diabetic range. The aim of this study is to profile the characteristics of these subgroups to estimate the factors involved in the development from normal glucose tolerance (NGT) via IFG to DM/IFH. Five hundred and sixty seven Japanese males were classified on the basis of 75 g OGTT into four groups, NGT, IFG, DM/IFH, and isolated impaired glucose tolerance (isolated IGT). Insulin secretion was evaluated by insulinogenic index, insulin sensitivity was evaluated by ISI composite, and insulin secretory patterns were compared additionally. IFG and DM/IFH subjects exhibited both lower insulin secretion and lower insulin sensitivity than NGT subjects. There was an insulin peak in NGT, IFG, and DM/IFH at 60 min, which did not occur in isolated IGT. Impaired early-phase and basal insulin secretion and decreased insulin sensitivity both are estimated as factors in progression from NGT via IFG to DM/IFH in these subjects. IFG and DM/IFH subjects have definite fasting hyperglycemia in contrast to isolated IGT subjects, 2-h glucose levels being maintained within the non-diabetic range partly by the insulin peak at 60 min.

Relationship between insulin resistance and effect of atorvastatin in non-diabetic subjects

BACKGROUND

Although insulin resistance (IR) is present in non-diabetic subjects, it is unknown whether IR affects statin treatment. We assessed the relationship between IR and the changes of lipid profile in patients with hyperlipidemia treated by atorvastatin.

METHODS

Forty-four non-diabetic patients were included. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. We used the value of 2.5 as the threshold for IR.

RESULTS

High-density lipoprotein (HDL) cholesterol at baseline was lower and triglyceride (TG) at baseline was higher in the IR group than in the nonIR group (p < 0.05). Changes in all lipid measurements did not differ between the two groups. HOMA-IR was correlated with HDL cholesterol at baseline and at follow-up and correlated with TG at baseline and at follow-up (r = -0.40, r = -0.53, r = 0.38, r = 0.35, p < 0.01, respectively). However, HOMA-IR did not associate with changes in total cholesterol, low-density lipoprotein cholesterol, HDL cholesterol, and TG.

CONCLUSION

The IR did not affect the degree of reduction in cholesterol by atorvastatin in non-diabetic subjects. The IR may influence hypertriglyceridemia greater than the effect of atorvastatin in non-diabetic subjects.

Increased triglyceride levels in a Japanese population living in southern Brazil

BACKGROUND

In the present study we investigated 96 individuals of Japanese descent living in southern Brazil (Cascavel-PR) in terms of triglyceride (TG) levels (> or < or = 200 mg/dL) and compared them to non-Japanese control individuals.

METHODS

We analyzed TG and total cholesterol (TC) levels by an enzymatic method and apolipoprotein A-I and B (apo A-I and apo B) by a turbidimetric method. We also determined the lipoproteins HDL and LDL by a direct method and by electrophoresis. All these determinations were performed in plasma.

RESULTS

TG levels were above 200 mg/dL in 18.7% of the individuals of Japanese descent and in 8.4% of the controls. Mean TC levels were 259 mg/dL for Japanese descendants and 225 mg/dL for the control group. We observed that individuals of Japanese descent with TG levels above 200 mg/dL had the highest TC, LDL-c, and VLDL-c levels and the lowest HDL-c and apo A-I levels. Body mass index (BMI) was also higher in individuals of Japanese descent with TG above 200 mg/dL.

CONCLUSIONS

This Japanese population has high TG levels compared to control individuals, and diet did not influence these levels.

Effects of Nurse-coordinated Intervention on Patients With Type 2 Diabetes in Korea

This study investigated the effects of a nurse-coordinated intervention on patients with type 2 diabetes in Korea. Fifteen patients were randomly assigned to an intervention group and 10 to a control group. The intervention was implemented for 12 weeks by telephone. Patients in the intervention group had a mean decrease of 1.2% in glycosylated hemoglobin (HbA(1C)) levels and those in the control group had a mean increase of 0.5%. Patients' satisfaction with care was higher in the intervention group than in the control group after the intervention. These findings indicated that the nurse-coordinated intervention could improve HbA(1C) levels and satisfaction with care in patients with type 2 diabetes in Korea.

Soluble E-selectin, leptin, triglycerides, and insulin resistance in nonobese Japanese type 2 diabetic patients

The aim of the present study was to investigate the relationships between insulin resistance and soluble E-selectin, body mass index (BMI), leptin, and serum lipid profile including triglycerides in nonobese Japanese type 2 diabetic patients. A total of 97 nonobese Japanese type 2 diabetic patients aged 43 to 84 years were examined. The duration of diabetes was 11.2 +/- 0.8 years. In conjunction with BMI and fasting concentrations of plasma glucose, serum lipids (triglycerides, total cholesterol, and high-density lipoprotein cholesterol) and serum insulin, soluble E-selectin, and leptin were also measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula. Insulin resistance was estimated by the homeostasis model assessment. The subjects were divided into 2 groups according to the value of insulin resistance estimated by the homeostasis model assessment. Values greater than 2.5 were indicative of the insulin-resistant state, and values less than 2.5 were indicative of the insulin-sensitive state. The insulin-resistant group had significantly higher levels of E-selectin, leptin, triglycerides, total and LDL cholesterol, and diastolic blood pressure as compared with the insulin-sensitive group. There was, however, no significant difference in age, sex, diabetes duration, BMI, systolic blood pressure, HbA1c, and high-density lipoprotein cholesterol between the 2 groups. Univariate regression analysis showed that insulin resistance was positively correlated to E-selectin (r = 0.305, P = .003), BMI (r = 0.283, P = .006), leptin (r = 0.296, P = .004), HbA1c (r = 0.241, P = .018), serum triglycerides (r = 0.385, P < .001), serum total (r = 0.240, P = .019) and LDL cholesterol (r = 0.254, P = .013) levels, and systolic (r = 0.247, P = .024) and diastolic (r = 0.305, P = .006) blood pressure. Multiple regression analyses showed that insulin resistance was independently predicted by serum E-selectin (F = 18.4), serum leptin (F = 14.0) and serum triglycerides (F = 20.0) levels, which explained 45.0% of the variability of insulin resistance. From these results, it can be concluded that in conjunction with serum triglycerides and serum leptin, serum E-selectin is another important independent factor associated with insulin resistance in nonobese Japanese type 2 diabetic patients.

Determinants of postprandial triglyceride and remnant-like lipoproteins in type 2 diabetes

BACKGROUND

Postprandial changes in remnant-like lipoprotein particles (RLP) contribute to the severity of coronary heart disease in type 2 diabetes. Since the determinants of postprandial response in RLP are not well understood, this study investigated the roles of fasting triglyceride, apolipoprotein (apo) E polymorphism and insulin resistance in a group of overweight/obese Chinese type 2 diabetic subjects.

METHODS

Postprandial triglyceride (TG) and RLP-cholesterol (RLP-C) were determined after a mixed meal containing 70-g fat at 2-h intervals for 8 h in 32 normotriglyceridemic (NTG) and 31 hypertriglyceridemic (HTG) subjects. RLP-C was measured using an immunoseparation assay and apo E genotypes using polymerase chain reaction and restriction mapping. Insulin resistance was defined as homeostasis model assessment index (HOMA-IR).

RESULTS

The HTG subjects had greater postprandial increase in TG and RLP-C than NTG (p < 0.001), but there were no significant differences in HOMA-IR and apo E allele frequencies. Subjects who were non-E3-carriers had the largest postprandial increment in TG and RLP-C. On stepwise linear regression analysis, log(HOMA-IR) was only an independent determinant of fasting TG but not postprandial TG or RLP-C. The major determinants of fasting and postprandial RLP-C were fasting TG and apo E genotype, accounting for 53 and 6% of the variance of fasting RLP-C (p < 0.01) and 31 and 13% of the variance of postprandial RLP-C respectively (p < 0.01).

CONCLUSIONS

Insulin resistance is mainly a determinant of fasting triglyceride in Chinese type 2 diabetic subjects, whereas apo E genotype is a better predictor of both fasting and postprandial concentrations of RLP.

High remnant lipoprotein levels in patients with variant angina

BACKGROUND

Dyslipidemia with increased oxidative stress but without elevation of low-density lipoprotein cholesterol has been recently implicated in the pathogenesis of coronary vasospasm.

HYPOTHESIS

Disordered triglyceride-rich lipoprotein metabolism may be linked to the genesis of coronary artery spasm.

METHODS

Both serum remnant lipoprotein (RLP) and alpha-tocopherol levels were determined in 18 patients with the active stage of variant angina (VA), in 16 patients with the inactive stage of variant angina (IVA), and in 19 control subjects (CONTROL).

RESULTS

The RLP levels were significantly (p < 0.05) higher in VA (6.4 +/- 2.7 mg/dl) than in IVA (4.4 +/- 1.5 mg/dl). In contrast, alpha-tocopherol levels were significantly lower in VA than that in CONTROL. Serum trigyceride levels were not significantly different among the study groups, although serum high-density lipoprotein cholesterol levels were significantly lower in VA than in CONTROL. Smoking was significantly (p < 0.05) more prevalent in VA (72%) than in IVA (25%) and CONTROL (37%). Serum RLP levels correlated positively with triglyceride levels (R = 0.73) and correlated inversely with alpha-tocopherol levels (R = -0.31) significantly in all study subjects.

CONCLUSIONS

Patients with active stage of variant angina had higher RLP levels than inactive patients with variant angina and lower alpha-tocopherol levels than control subjects. Disordered triglyceride-rich lipoprotein metabolism with increased oxidative stress appears to be linked to the activity of coronary vasospasm, suggesting a possible role in its pathogenesis.

Adiponectin gene polymorphism (G276T) is not associated with incipient diabetic nephropathy in Japanese type 2 diabetic patients

A single-nucleotide polymorphism (SNP) G276T in the adiponectin gene has been associated with lower plasma adiponectin levels and insulin resistance, which are related to the prevalence of type 2 diabetes or diabetic complications of macroangiopathy. We performed a case-control study to examine whether the SNP276 of the adiponectin gene was also related to early diabetic nephropathy. SNP276 was examined with genomic DNA obtained from 108 type 2 diabetic patients with microalbuminuria (urinary albumin creatinine ratio [ACR] between 30 mg/g x Cr and 300 mg/g x Cr; case subjects), and 208 patients with normoalbuminuria (ACR < 30 mg/g x Cr; control subjects). The genotype distribution and G allele frequency of SNP276 in the case subjects (0.71) did not significantly differ from the control subjects (0.69). There were no differences among the genotypes of the adiponectin gene regarding age, duration of diabetes, body mass index (BMI), hemoglobin A(1c) (HbA(1c)), serum lipids, serum creatinine, and plasma adiponectin levels. These data suggest that SNP276 of the adiponectin gene is not an independent risk factor for incipient diabetic nephropathy in Japanese type 2 diabetic patients.

Insulin secretion and insulin sensitivity at different stages of glucose tolerance: a cross-sectional study of Japanese type 2 diabetes

To evaluate the factors causing glucose intolerance in type 2 diabetes in Japan, insulin secretion and insulin sensitivity were compared across the range of glucose tolerance. Subjects were divided into 3 groups: normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes (DM) according to the criteria of the World Health Organization (WHO). We examined insulin secretion and insulin sensitivity using fasting blood glucose and insulin levels and 75 g oral glucose tolerance test (OGTT). We used homeostasis model assessment (HOMA) beta-cell and insulinogenic index (30 minutes) to estimate insulin secretion and HOMA-insulin resistance (IR) and insulin sensitivity index (ISI) composite for insulin sensitivity. Although insulin resistance plays an important role in the development of diabetes in many ethnic populations, the differences in insulin sensitivity between NGT and IGT and between IGT and DM are small in Japanese patients. On the other hand, as glucose intolerance increases, insulin secretion decreases most remarkably both between NGT and IGT and between IGT and DM in Japanese patients. Decreasing insulin secretion and decreasing insulin sensitivity both occur in developing type 2 diabetes in Japanese patients, but decreased basal and early-phase insulin secretion had more pronounced contribution to glucose tolerance than the indices of insulin sensitivity. Japanese type 2 diabetic patients are characterized by a larger decrease in insulin secretion and show less attribution of insulin resistance.

IGT with fasting hyperglycemia is more strongly associated with microalbuminuria than IGT without fasting hyperglycemia

Previous studies have established that impaired glucose tolerance (IGT) patients with fasting hyperglycemia (IGT/FH: fasting plasma glucose (FPG) level 6.1-7.0 mmol/l and 2 h PG level of 7.8-11.1 mmol/l) exhibit higher insulin resistance than those with isolated IGT (FPG level <6.1 mmol/l and 2 h PG level of 7.8-11.1 mmol/l), but the association with microalbuminuria has not been determined. Here, we evaluate the prevalence of microalbuminuria in non-diabetic Japanese males 20-70 years of age. The subjects were classified into four groups based on the results of OGTT: normal glucose tolerance (NGT: n=71), impaired fasting glucose (IFG: n=24), isolated IGT (n=36), and IGT/FH (n=23). A urinary albumin-to-creatinine ratio (ACR) from 30 to 300 microg/mg creatinine was counted as microalbuminuria. The prevalence of microalbuminuria was higher in subjects with IGT/FH than in subjects with isolated IGT (26% versus 14%). Logistic regression analysis showed microalbuminuria to be more significantly associated with IGT/FH (OR=3.82, 95% CI 1.09-13.36) than with isolated IGT (OR=1.75, 95% CI 0.50-6.17). While insulin resistance (HOMA-IR) in isolated IGT was not significantly different from that in NGT, insulin resistance in IGT/FH was significantly higher (P<0.01). Regression analysis of ACR in IGT showed a significant correlation with insulin resistance (P=0.012). Accordingly, microalbuminuria is more strongly associated with IGT/FH than with isolated IGT, most likely due to the higher insulin resistance.

The close relationship between postprandial remnant metabolism and insulin resistance

The aim of this study was to investigate the relationship between postprandial remnant-like particle (RLP) metabolism and insulin resistance (IR). The study group consisted of 52 randomly selected subjects. To evaluate postprandial hyperlipidemia, serum lipid and lipoprotein concentrations during fasting and 4h after the fat-loading test were measured in each subject. IR was assessed using the index of homeostasis model assessment (HOMA-R). The subjects were divided into two groups according to the value of HOMA-R: an IR group (n=17) with a HOMA-R value >/=1.73, and a normal (NR) group (n=35) with a HOMA-R value <1.73. Both fasting and postprandial RLP-cholesterol (RLP-C) concentrations were higher in the IR group than in the NR group (6.2+/-2.6 versus 4.1+/-1.7mg/dl fasting value, and 9.7+/-4.0 versus 5.8+/-2.9mg/dl postprandial value). The changes in RLP-C concentration during the fat-loading test were twice as high in the IR group compared with the NR group (3.5+/-2.4 versus 1.6+/-1.6mg/dl, P=0.0022). The HOMA-R correlated significantly with both fasting and postprandial triglyceride (r=0.41 and 0.43, respectively) and RLP-C (r=0.36 and 0.50, respectively) in all subjects. Multiple regression analysis indicate that postprandial RLP-C concentration was an independent predictor of HOMA-R regardless of age, BMI, and other lipid profiles. Thus, postprandial RLP metabolism is closely related to IR. Atherosclerotic proliferation in IR syndrome may be caused by the accumulation of postprandial remnant lipoproteins after the daily fat intake.

Body mass index is the most important determining factor for the degree of insulin resistance in non-obese type 2 diabetic patients in Korea

With obesity, increased insulin secretion is needed to compensate for the additional demands and to maintain euglycemia. In contrast to Caucasians, the majority of type 2 diabetic patients belong to the non-obese category in Korea. There appears to be an ethnic difference underlying the pathogenesis in type 2 diabetes mellitus. However, there is only limited data on these subjects. The degree of insulin resistance in 267 Korean non-obese (body mass index [BMI] < 25 kg/m(2)) >/= patients with type 2 diabetes mellitus was analyzed, and the factors responsible for the insulin resistance were examined. The mean age and BMI of the patients were 50.8 +/- 10.6 years and 22.6 +/- 1.8 kg/m(2). Homeostasis model assessment-insulin resistance (HOMA-IR) >/= 2.5 was defined as being insulin resistant according to our data (mean +/- 1.5 SD of 1,917 normal subjects). There was no significant difference according to age, the duration of disease, and the glycosylated hemoglobin (HbA(lc)) levels between the subjects with or without insulin resistance. The HOMA-IR values in the patients with insulin resistance and normal insulin sensitivity were 4.2 +/- 1.4 and 1.5 +/- 0.6, respectively. In the insulin-resistant group, the log-transformed triglyceride (TG) levels were higher and the high-density lipoprotein-cholesterol (HDL-C) levels were lower than those of the insulin-sensitive group (log-transformed TG: 5.2 +/-.6 v 4.9 +/-.7 and HDL-C: 1.13 +/- 0.3 v 1.25 +/- 0.3mmol/L). These differences were still observed after adjusting for BMI. The HOMA-IR value was independently predicted by BMI and HDL-C levels, which explained 7% and 3% in the variability of insulin resistance, respectively. However, the TG levels were not independently associated with the HOMA-IR. Logistic regression analysis showed that the significant factor associated with HOMA-IR was only BMI. These results suggest that the BMI is the most important determinant of insulin resistance, while TG and HDL-C levels might be good markers of insulin resistance in non-obese patients with type 2 diabetes mellitus in Korea.

Unilateral adrenalectomy improves insulin resistance and diabetes mellitus in a patient with ACTH-independent macronodular adrenal hyperplasia

ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a rare cause of Cushing's syndrome. Bilateral adrenalectomy is considered to be a standard therapy for AIMAH, although lifetime replacement of glucocorticoids is necessary after the procedure. This paper describes a subject with AIMAH who underwent unilateral adrenalectomy of the predominantly enlarged gland and subsequently displayed an improvement in insulin resistance and diabetes mellitus, the cardinal symptoms before the operation, concomitant with alleviation of abnormal cortisol secretion. The patient was a 61-year-old man with a body mass index of 25.6 kg/m2. He was diagnosed as having diabetes mellitus, hypertension, and hyperlipidemia at 50 years of age. Eight years after diagnosis, bilateral enlargement of the adrenal glands was revealed by chance upon computed tomography of the abdomen. Typical manifestations of Cushing's syndrome were not demonstrated. Basal levels of serum and urinary cortisol had not increased, although the serum cortisol level displayed no circadian rhythm and no response to the administration of dexamethasone. Despite sulfonylurea treatment, the patient's HbA1C level was as high as 7.6% (normal range 4.3-5.8%). Fasting insulin concentration was increased to 42.6 microU/ml, and the homeostasis model insulin resistance index (HOMA-R) was calculated to be 15.5 (with a normal range of less than 2.5), indicating severe insulin resistance. Unilateral adrenalectomy of the predominantly enlarged gland revealed that the resected gland consisted of multiple nodules of various sizes. Based on endocrinological, radiological, and pathological findings, a diagnosis of AIMAH was made. Ten months after the unilateral adrenalectomy, cortisol circadian rhythms were restored, and serum cortisol concentration was suppressed in response to the administration of low doses of dexamethasone, suggesting an improvement in the cortisol secretory pattern. Levels of HbA1C, fasting insulin, and HOMA-R decreased to 5.7%, 12.7 microU/ml, and 2.2, respectively. An improvement in hyperlipidemia was also observed. Insulin resistance and glucose intolerance are recognized as features of mild hypercortisolism. In the present case, unilateral adrenalectomy was effective in ameliorating insulin resistance and improving glycemic control. Unilateral adrenalectomy might be an alternative therapy for improvement of glucose and lipid metabolism in subjects with AIMAH.

Insulin sensitivity and Lp(alpha) concentrations in normoglycemic offspring of type 2 diabetic parents

Background

Offspring of at least 1 parent with type 2 diabetes are more resistant to the insulin action, exhibit higher incidence of dyslipidemia and are more prone to cardiovascular diseases. The association between Lp(α) and coronary heart disease is well established. An association between Lp(α) concentration and insulin sensitivity was examined in this study.

We investigated the serum LP(α) in 41 offspring of 41 families of type 2 diabetic subjects (group I) with normal glucose tolerance, compared to 49 offspring who their parents had no history of type 2 diabetes, matched for sex, age, BMI, WHR and blood pressure (group II). Serum Lp(α), triglycerides, insulin resistant index, HDL, LDL-cholesterol and insulin were measured.

Results

The offspring of type 2 diabetic subjects had higher fasting serum triglycerides (mean ± SD 199.3 ± 184.2 vs. 147.1 ± 67.9 ng/dl, p < 0.05) lower HDL-cholesterol (37.3 ± 9.0 vs. 44.6 ± 7.8, p < 0.001) and particularly higher Insulin resistance Index (HOMA-IR) (2.84 ± 1.39 vs. 1.67 ± 0.77, p < 0.001).

They also had higher serum LP(α) concentration (15.4 ± 6.7 vs. 8.6 ± 6.0, p < 0.001). By simple linear analysis in the offspring of type 2 diabetic parents there was no correlation of Lp(α) concentration with insulin resistance index Homa-IR (r = 0,016 p = NS).

Conclusions

We conclude that serum LP(α) is significantly increased in offspring of type 2 diabetic subjects but was not related to insulin sensitivity.

Platelet count is independently associated with insulin resistance in non-obese Japanese type 2 diabetic patients

The aim of the present study was to investigate the relationship between platelet count and insulin resistance in non-obese Japanese type 2 diabetic patients. A total of 163 non-obese Japanese type 2 diabetic patients (112 men and 51 women, aged 36 to 84 years, body mass index [BMI] 16.2 to 26.9 kg/m(2)) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA(1c)), fasting concentrations of plasma glucose and serum lipids (triglycerides, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, and total cholesterol), and hematological parameters (platelets, white blood cell count, red blood cell count, hematocrit, hemoglobin) were measured. LDL cholesterol was calculated using the Friedewald formula. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Univariate regression analysis showed that HOMA-IR was positively correlated to BMI (r = 0.465, P <.0001), HbA(1c) (r = 0.423, P <.0001), platelet count (r = 0.310, P <.0001), triglycerides (r = 0.277, P <.0005), white blood cell count (r =.222, P =.005), red blood cell count (r = 0.210, P =.008), hematocrit (r = 0.156, P =.047), total cholesterol (r = 0.178, P =.023), and systolic (r = 0.216, P =.011) and diastolic (r = 0.263, P =.002) blood pressure, and inversely correlated to HDL cholesterol (r = -0.312, P <.0001) level in our diabetic patients. Multiple regression analysis showed that HOMA-IR was independently predicted by BMI (P <.0001, F = 22.45), HbA(1c) (P <.0001, F = 16.15), platelet count (P <.0001, F = 10.75), and serum triglycerides (P <.0001, F = 10.47) levels, which explained 34% of the variability of HOMA-IR in non-obese Japanese type 2 diabetic patients. These results indicate that not only BMI, HbA(1c), and triglycerides levels but also platelet counts are independent predictor of insulin resistance in non-obese Japanese type 2 diabetic patients.

Hypoadiponectinemia is associated with visceral fat accumulation and insulin resistance in Japanese men with type 2 diabetes mellitus

The aim of the present study was to investigate the association of serum adiponectin concentration with regional adiposity and insulin resistance in subjects with type 2 diabetes mellitus. A total of 73 Japanese men with type 2 diabetes (aged 59 +/- 11 years and body mass index [BMI] 23.8 +/- 3.0 kg/m(2), mean +/- SD) were studied. Fasting serum adiponectin and leptin concentrations were determined by radioimmunoassay. Regional adiposity was measured by abdominal computed tomography (CT) at the umbilical level, and insulin resistance was estimated by homeostasis model assessment (HOMA-R). Univariate regression analysis showed that serum adiponectin levels were negatively correlated with subcutaneous and visceral fat areas. With multivariate regression analysis, visceral fat area was a predominant determinant of serum adiponectin levels. In contrast, subcutaneous fat area was strongly associated with serum leptin concentrations. Among subcutaneous and visceral fat areas, BMI, and serum leptin levels, both subcutaneous and visceral fat areas were independently associated with HOMA-R. In another model incorporating serum adiponectin levels, serum adiponectin levels were selected as an independent determinant of HOMA-R instead of visceral fat area. In conclusion, hypoadiponectinemia was associated with visceral fat accumulation rather than subcutaneous fat depot in Japanese men with type 2 diabetes mellitus. Both subcutaneous and visceral fat accumulation contribute to insulin resistance in these subjects, and the contribution of visceral fat may be mediated, in part, by hypoadiponectinemia.

Increased visceral fat and serum levels of triglyceride are associated with insulin resistance in Japanese metabolically obese, normal weight subjects with normal glucose tolerance

OBJECTIVE

The purpose of this study was to investigate the association between visceral adiposity or triglyceride (TG) metabolism and insulin resistance in metabolically obese, normal weight (MONW) Japanese individuals with normal glucose tolerance.

RESEARCH DESIGN AND METHODS

We evaluated body fat areas, lipid profiles, and the glucose infusion rate (GIR) during a euglycemic-hyperinsulinemic clamp study in 20 MONW subjects (BMI <25 kg/m(2)and visceral fat areas 100 cm(2)) with normal glucose tolerance. Body fat areas were measured by computed tomography scans. Control data were obtained from 20 normal subjects (BMI <25 kg/m(2) and visceral fat areas <100 cm(2)).

RESULTS

MONW subjects showed a significant increase in fasting serum levels of TG (P < 0.01) and a decrease in GIR (P < 0.01) compared with normal subjects. There were significant correlations between visceral fat areas (r = -0.563, P < 0.01) or serum levels of TG (r = -0.474, P < 0.05) and GIR in MONW subjects. Multiple regression analyses showed that visceral fat areas (F = 7.702, P < 0.02) and serum levels of TG (F = 7.114, P < 0.05) were significantly associated with GIR in all (MONW and normal) subjects.

CONCLUSIONS

Increased visceral fat and serum levels of TG are associated with insulin resistance in Japanese MONW subjects with normal glucose tolerance. Excess visceral fat and elevated TG levels may play important roles in the development of insulin resistance in Japanese MONW subjects with normal glucose tolerance.

Factors responsible for development from normal glucose tolerance to isolated postchallenge hyperglycemia

OBJECTIVE

Isolated postchallenge hyperglycemia (IPH), defined as fasting plasma glucose (FPG) level <7.0 mmol/l and 2-h plasma glucose (PG) level >/=11.1 mmol/l, is a subtype of early-stage diabetes. This study evaluates the metabolic profiles of insulin secretion and insulin sensitivity in IPH to clarify the factors responsible for development of this form of type 2 diabetes.

RESEARCH DESIGN AND METHODS

We conducted cross-sectional analysis of 231 Japanese men aged 20-70 years. The subjects were classified into the following three groups, based on the results of a 75-g oral glucose tolerance test (OGTT): 1) normal glucose tolerance (NGT), defined as FPG level <6.1 mmol/l and 2-h PG level <7.8 mmol/l (n = 89); 2) impaired glucose tolerance (IGT), defined as FPG level <7.0 mmol/l and 2-h PG level of 7.8-11.1 mmol/l (n = 94); and 3) IPH (n = 48). We compared the three groups for insulin secretion (insulinogenic index) and insulin sensitivity (index of insulin resistance using homeostasis model assessment [HOMA-IR]).

RESULTS

The insulinogenic index in IPH was the lowest of the three groups (P < 0.001 versus NGT). The HOMA-IR in the IGT and IPH groups were significantly higher than in the NGT group (P < 0.001), but both were similar. By linear regression analysis, the insulinogenic index rather than fasting insulin or HOMA-IR was the more significant factor in the 2-h PG level in IGT and IPH.

CONCLUSIONS

Subjects with IPH exhibited distinctly impaired early-phase insulin secretion and only mild insulin resistance, indicating that reduced insulin secretion is the primary determinant of deterioration from NGT to IGT and IPH in development of type 2 diabetes in these subjects.

Relationship of regional adiposity to serum leptin level in nonobese Japanese type 2 diabetic male patients

BACKGROUND

The aim of the present study was to investigate the relationships between serum leptin levels and regional adipose fat area, BMI, and the measures of variables including serum insulin in nonobese Japanese type 2 diabetic patients.

METHODS

A total of 121 nonobese Japanese type 2 diabetic patients [aged 35 to 83 years, body mass index (BMI) (15.4 to 26.8 kg/m(2))] were studied. They all were male patients. In conjunction with serum leptin level, BMI, glycosylated hemoglobin (HbA(1c)), and fasting concentrations of plasma glucose and serum insulin and lipids (triglycerides, total and HDL cholesterol) were measured.

RESULTS

Univariate regression analysis showed that serum leptin levels were positively correlated to subcutaneous (r=0.566, P<0.0001) and visceral (r=0.481, P<0.001) fat area in our diabetic patients. Furthermore, serum leptin levels were positively correlated to serum insulin (r=0.517, P<0.0001), BMI (r=0.428, P<0.0001), serum triglycerides (r=0.279, P<0.005), and age (r=0.225, P<0.05). There was, however, no relationship between serum leptin levels and measures of other variables including total and HDL cholesterol. Multiple regression analyses showed that serum leptin levels were predicted by subcutaneous fat area (F=5.92, P<0.0001) and serum insulin level (F=5.60, P<0.0001), which explained 29.0% of the variability of serum leptin concentrations in our nonobese Japanese type 2 diabetic male patients. Visceral fat area, BMI, serum triglycerides, and age, however, were not independently associated with serum leptin levels in our patients.

CONCLUSIONS

These results indicate that serum leptin levels are reflective of subcutaneous fat area in nonobese Japanese type 2 diabetic male patients.

Porphyromonas gingivalis infection is associated with carotid atherosclerosis in non-obese Japanese type 2 diabetic patients

The aim of the present study was to investigate whether non-obese Japanese type 2 diabetic patients with porphyromonas gingivalis infection have atherosclerotic vascular diseases. A total of 134 non-obese Japanese type 2 diabetic patients (96 men and 38 women, aged 36 to 84 years, body mass index [BMI] 20.1 to 26.9 kg/m(2)) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA(1c)), fasting glucose, and serum lipids (triglycerides, total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol) were measured. LDL cholesterol was calculated using the Friedewald formula. Using high-resolution B-mode ultrasound scan, we measured intimal medial thickness (IMT) in plaque-free segments of bilateral common carotid arteries, and the mean of IMT in 2 vessels was used for the analysis. Furthermore, we calculated the degree of stenosis in plaque segments of bilateral common carotid arteries. The degree of carotid atherosclerosis was expressed as a percentage ratio between the area of plaque and that of the lumen using the formula (Lumen Area Residual - Lumen Area)/Lumem Area x 100. Both the areas were automatically measured by the system on a frozen transverse scanning plane at the site of maximal narrowing. When 2 or more plaques were present in the vessel, only that causing the greatest degree of stenosis was considered for analysis. Values represent mean+/-SEM unless otherwise stated. Immunoglobulin G (IgG) titer against porphyromonas gingivalis was 245 +/- 65 (mean +/- 2 SD) in nondiabetic healthy subjects. In contrast, there was a wide variation in IgG titer against porphyromonas gingivalis in type 2 diabetic patients studied (range, 16 to 26,800). Thus, we classified our type 2 diabetic patients into 2 subpopulations according to the value of mean +/- 2 SD (= 310) of nondiabetic healthy subjects: one with high IgG titer against porphyromonas gingivalis (>310) (1,422 +/- 408) and the other with normal IgG titer against porphyromonas gingivalis (<310) (152 +/- 10, P =.002). The populations did not differ with respect to age, sex, BMI, fasting glucose, HbA(1c), serum triglycerides, total, HDL, and LDL cholesterol levels. Although the mean IMT in plaque-free segments was not different between the 2 groups (0.73 +/-0.03 v 0.68 +/- 0.02 mm, P =.098), the degree of stenosis in plaque segments was significantly higher in the high IgG titer group (12.0% +/- 2.2%) than in normal one (5.5% +/- 1.4%, P =.009). From these results, it can be concluded that porphyromonas gingivalis infection, although still a subclinical infection, is associated with atherosclerotic vascular disease in non-obese Japanese type 2 diabetic patients.

Impaired beta-cell function and insulin sensitivity in Japanese subjects with normal glucose tolerance

The development of type 2 diabetes mellitus is characterized by both impaired beta-cell function and increasing insulin resistance. To clarify the roles of them in developing type 2 diabetes, we evaluated insulin resistance by HOMA-IR and insulin secretion by HOMA beta-cell in 453 Japanese subjects whose fasting plasma glucose (FPG) and HbA(1c) levels were within normal range. HOMA beta-cell was found to decrease in the over 30 years groups, while HOMA-IR increased with body mass index (BMI). To analyze the reserve capacity of insulin secretion and insulin sensitivity, the 67 of them, who underwent a standard oral glucose tolerance test and were diagnosed with normal glucose tolerance (NGT), were divided into four degrees of BMI age-adjusted to 50 years. They were compared for insulinogenic index and ISI composite proposed by Matsuda and DeFronzo across the range of BMI. ISI composite was significantly less in the highest BMI group, while insulin secretion did not increase in the higher BMI groups. The subjects with higher BMI had remarkably lower insulinogenic indices than those with lower BMI. These data suggest that insulin secretory reserve is insufficient to compensate for increased insulin resistance in Japanese people with NGT at about 50 years of age.

Relationship between insulin-resistance and remnant-like particle cholesterol

We investigated the relationship between insulin-resistance (IR) and remnant-like particle cholesterol (RLP-C) using 472 subjects (174 men and 298 women) randomly selected from inhabitants of two rural communities in Japan, Tanno and Sobetsu. The level of fasting immunoreactive insulin (FIRI), fasting blood glucose (FBS), total cholesterol (TC), triglyceride (TG), HDL cholesterol, LDL cholesterol, and RLP-C were measured in each subject. Homeostasis model assessment (HOMA-R) was used as an indicator of IR. The subjects were divided into two groups according to the value of HOMA-R: an IR group of subjects with HOMA-R > approximately equal to 1.73 and a normal (NR) group of subjects with HOMA-R <1.73. There was a significant positive correlation between HOMA-R and RLP-C. The value of RLP-C was higher in the IR group than in the NR group (7.1 vs. 3.9 mg/dl in men and 5.3 vs. 3.6 mg/dl in women). The frequency of hyper RLP cholesterolemia (RLP-C > approximately equal to 7.5 mg/dl) was higher in the IR than in the NR group (23.7 vs. 6.6% in men and 20.3 vs. 6.6% in women). The results of multiple regression analysis showed that HOMA-R was closely related to RLP-C. The results of this study suggest that RLP-C is closely associated with IR syndrome.