Higher circulating orosomucoid, an acute-phase protein, and reduced glucose-induced insulin secretion in middle-aged Japanese people with prediabetes

The different associations of serum gamma-glutamyl transferase and alanine aminotransferase with insulin secretion, β-cell function, and insulin resistance in non-obese Japanese

The present study investigated the associations of serum gamma-glutamyl transferase (GGT), a marker of fatty liver and oxidative stress, and ALT/AST, a marker of fatty liver, with percentage trunk fat and postload glucose, insulin resistance, and β-cell function in middle-aged Japanese individuals, whose BMI averaged < 23.0 kg/m2. Pancreatic β-cell function was assessed using the disposition index calculated by a product of the insulinogenic index (IGI) and Matsuda insulin sensitivity index, a biomarker of early-phase glucose-stimulated insulin secretion and whole-body insulin sensitivity, respectively. Multivariate linear regression analyses revealed that the disposition index was associated inversely with GGT independently of percentage trunk fat, homeostasis model assessment insulin resistance (HOMA-IR), a marker of insulin resistance, and Matsuda index. When IGI was included instead of the disposition index, IGI (inversely) and HOMA-IR were associated with GGT independently of percentage trunk fat and Matsuda index. When the area under the glucose concentration curve (AUCg) during an oral glucose tolerance test was included instead of the disposition index, AUCg and HOMA-IR emerged as independent determinants of GGT. ALT/AST was associated with HOMA-IR alone. Results suggest a different pathophysiologic basis between GGT and ALT/AST in predicting diabetic risk in non-obese Japanese.

Associations of adipose insulin resistance index with pancreatic β cell function (inverse) and glucose excursion (positive) in young Japanese women

The relationship of adipose tissue insulin resistance (AT-IR, a product of fasting insulin and free fatty acids) and homeostasis-model assessment-insulin resistance (HOMA-IR) to β-cell function was studied cross-sectionally in the setting of subtle glucose dysregulation. Associations of AT-IR and HOMA-IR with fasting and post-glucose glycemia and β-cell function inferred from serum insulin kinetics during a 75 g oral glucose tolerance test were studied in 168 young female Japanese students. β-cell function was evaluated by disposition index calculated as a product of the insulinogenic index (IGI) and Matsuda index. AT-IR, not HOMA-IR, showed positive associations with post-glucose glycemia and area under the glucose response curve although both indices were associated with fasting glycemia. HOMA-IR, not AT-IR, was associated positively with log IGI whereas both indices were inversely associated with Matsuda index. AT-IR, not HOMA-IR, showed inverse associations with log disposition index. Associations of adipose tissue insulin resistance with β-cell function (inverse) and glucose excursion in young Japanese women may suggest that lipotoxicity to pancreatic β-cells for decades may be associated with β cell dysfunction found in Japanese patients with type 2 diabetes. Positive association of HOMA-IR with insulinogenic index may be associated with compensatory increased insulin secretion.

Associations of Alanine Aminotransferase/Aspartate Aminotransferase, a Marker of Hepatosteatosis, with Adipose Tissue Insulin Resistance Index and Leptin/Adiponectin Ratio in Japanese Women

Objective: We assessed whether alanine aminotransferase/aspartate aminotransferase (ALT/AST), a marker of hepatic steatosis, may be associated with adipose tissue dysfunction more closely than hepatic and muscle insulin resistance (IR). Methods: Associations with adipose tissue IR index (AT-IR) calculated as a product of fasting insulin and free fatty acids, leptin/adiponectin ratio, a proxy of adipocyte dysfunction, homeostasis model assessment IR (HOMA-IR), hepatic and muscle IR inferred from plasma insulin kinetics during a 75 grams oral glucose tolerance test (OGTT) were studied in nondiabetic 307 young and 148 middle-aged Japanese women, whose body mass index averaged 20 and 22 kilograms/m2, respectively. Results: On multivariate linear regression analysis in young women, ALT/AST was associated with trunk/leg fat ratio (standardized β = 0.202, P = 0.007), a marker of abdominal fat accumulation, and AT-IR (standardized β = 0.185, P = 0.003) independently of HOMA-IR and Matsuda index (R2 = 0.07). In middle-aged women, leptin/adiponectin ratio (standardized β = 0.446, P < 0.001) and AT-IR (standardized β = 0.292, P = 0.009) emerged as determinants of ALT/AST independently of trunk/leg fat ratio, OGTT-derived hepatic IR, leptin, and adiponectin (R2 = 0.34). Conclusions: ALT/AST was associated with AT-IR and adipocyte dysfunction more closely than hepatic and muscle IR even in nondiabetic lean Japanese women.

Associations of alanine aminotransferase/aspartate aminotransferase with insulin resistance and β-cell function in women

We tested whether alanine aminotransferase/aspartate aminotransferase (ALT/AST), a marker of hepatosteatosis, associates with insulin resistance, β-cell function and postglucose glycemia. We studied 311 young and 148 middle-aged Japanese women, whose BMI averaged < 23.0 kg/m2. Insulinogenic index and Matsuda index were evaluated in 110 young and 65 middle-aged women. In two groups of women, ALT/AST was associated positively with homeostasis model assessment insulin resistance (HOMA-IR) and inversely with Matsuda index. In middle-aged women only, the ratio was also associated positively with fasting and postload glycemia and HbA1c. The ratio showed negative association with disposition index (a product of insulinogenic index and Matsuda index). On multivariate linear regression analysis, HOMA-IR emerged as a single determinant of ALT/AST in young and middle-aged women (standardized β: 0.209, p = 0.003 and 0.372, p = 0.002, respectively). ALT/AST was associated with insulin resistance and β-cell function even in non-obese Japanese women, suggesting a pathophysiologic basis in its prediction of diabetic risk.

Serum Orosomucoid Is Associated with Serum Adiponectin, Adipose Tissue Insulin Resistance Index, and a Family History of Type 2 Diabetes in Young Normal Weight Japanese Women

INTRODUCTION

Adipose tissue (AT) expandability may be facilitated by adiponectin and suppressed by orosomucoid, and reduced AT expandability may be associated with first-degree relatives of type 2 diabetes. We tested the hypothesis that orosomucoid may be associated not only with adiponectin and adipose tissue insulin resistance but also with a family history of type 2 diabetes (FHD). Research Design and Methods. Anthropometric and metabolic variables, adipokines, and measures of inflammatory and insulin resistance were cross-sectionally investigated in 153 young normal weight Japanese women. Stepwise multivariate linear regression analyses were used to identify the most important determinants of orosomucoid.

RESULTS

Orosomucoid was higher in women with positive (n = 57) compared to women with negative FHD and was associated positively with FHD (both p = 0.01). Orosomucoid also showed positive associations with fasting glucose (p < 0.001), free fatty acids (p = 0.001), and HbA1c (p = 0.007), whereas there was no association with fasting insulin and serum lipids. In addition, orosomucoid was associated inversely with adiponectin (p = 0.02) and positively with adipose tissue-insulin resistance index (AT-IR, the product of fasting insulin and free fatty acids; p = 0.001) but not with homeostasis model assessment-insulin resistance, leptin, and high-sensitivity C-reactive protein. In multivariate analyses, AT-IR (standardized β, 0.22; p = 0.003), serum adiponectin (standardized β, -0.163; p = 0.032), FHD+ (standardized β, 0.178; p = 0.029), and HbA1c (standardized β, 0.213; p = 0.005) emerged as independent determinants of orosomucoid and explained 15.2% of its variability.

CONCLUSIONS

These results are the first to demonstrate that orosomucoid is associated not only with adipose tissue-insulin resistance and adiponectin but also with FHD.