Effect of body mass index on insulin secretion or sensitivity and diabetes

Dietary and lifestyle patterns identified through reduced rank regression and their association with insulin-related disorders: a prospective analysis from the Tehran Lipid and Glucose Study

BACKGROUND

Since foods are consumed in combinations that also interact with other lifestyle variables such as body mass index(BMI) and physical activity, it is difficult to separate the role of single foods or a lifestyle variable alone in predicting the risk of chronic diseases such as metabolic disorders. Therefore, a suitable way to examine the combined effect of food consumption and its interaction with other lifestyle variables is to derive dietary patterns and lifestyle patterns using appropriate statistical methods. This study aimed to derive two dietary and lifestyle patterns related to hyperinsulinemia and insulin resistance(IR) using reduced rank regression(RRR) analysis.

METHODS

The current study was conducted on 1063 individuals aged ≥ 25 years old of the Tehran Lipid and Glucose Study who have complete data on fasting blood sugar, plasma insulin, anthropometric variables, and nutritional intakes. Dietary intakes were collected using a food frequency questionnaire. Dietary and lifestyle patterns were identified via RRR analysis, using 34 food groups, BMI, smoking, and physical activity as predictor variables, and fasting serum insulin and HOMA-IR as response biomarkers.

RESULTS

RRR derived a dietary pattern with a higher intake of processed meat, doogh, pickles, lemon juices, fish, and a lower intake of starchy vegetables, garlic and onion, dried fruits, nuts, red meat, dairy products, and coffee as predictive variables for IR and hyperinsulinemia. Also, RRR derived a lifestyle pattern based on the above-mentioned dietary pattern and high BMI as response variables. In the final adjusted model of cross-sectional analysis, the odds of hyperinsulinemia(OR:1.23,95%CI:1.08-1.41,Ptrend=0.002) and IR(OR:1.52,95%CI:1.25-1.86,Ptrend<0.001) were elevated with increasing each quartile of RRR-derived dietary pattern score. Also, a higher adherence to RRR-derived lifestyle pattern was associated with higher odds of hyperinsulinemia(OR:2.49,95%CI:2.14-2.88,Ptrend<0.001) and IR(OR:3.20,95%CI:2.50-4.10,Ptrend<0.001). Moreover, after three years of follow-up, the risk of hyperinsulinemia(OR:1.30,95%CI:1.08-1.56,Ptrend=0.006) and IR(OR:1.26,95%CI:1.01-1.58,Ptrend=0.037) incidence were increased per each quartile increase of the RRR-derived lifestyle pattern.

CONCLUSIONS

Our findings suggested that a dietary pattern and lifestyle with elevated BMI level, higher consumption of processed meat, doogh, pickles, lemon juices, and fish, and lower consumption of starchy vegetables, garlic and onion, dried fruits, nuts, red meat, dairy products, coffee may be associated with a higher risk of hyperinsulinemia and IR. It is suggested that further studies with a larger sample size and more extended follow-up duration, especially in other populations with different lifestyles and food habits be performed to confirm the findings of the current study.

Reinstating acute-phase insulin release among sedentary adults at high risk for type 2 diabetes with Yoga and Walking based lifestyle modification

BACKGROUND

We compared the impact of 2 lifestyle modifying physical activities, yoga (YBLM) or walking (WBLM) on impaired beta cell function (IBF) or insulin resistance (IR) in restoring acute phase insulin release (APIR) among prediabetes at high risk for type 2 diabetes (HRDM).

METHOD

Male and female adults (N = 42, 38.1 ± 4.8 years) with abdominal obesity (Male:103 ± 8.1 cm) Female: 92 ± 11.1 cm), randomized into YBLM (n = 20) and WBLM (n = 22), were monitored for the practice of the intervention, 45 min a day/5 days a week for 12 weeks. Blood sample was collected at 0th minute to estimate the level of Fasting Blood Glucose (FBG), Sr. Insulin and lipid profile and at 10th minute (APIR). IBF, IR and sensitivity (IS) reading were checked in HOMA-2 calculator.

RESULT

Wilcoxon sign rank t-test denoted an improved APIR among the subjects with IBF (p = 0.008) and not among the subjects with IR (p = 0.332). However, regression analysis yielded an improved APIR among subjects with IBF (F(1,10) = 7.816, p = 0.002) with the management of body weight and lipid profile and IR (F(1,13) = 17.003, p = 0.001) being found influenced with selected lipid components. In all, during the post assessment period, an impressive boost in APIR was manifested among people shifted to Normoglycemia (n = 14, 35.9%).

CONCLUSION

Intriguingly, we postulate the potential role of YBLM over WBLM in the management of lipid profile and body weight on accelerating APIR either through improved Beta cell compensation or by sensitizing skeletal muscles regulating IR, helping improve glucose tolerance resulting in either remission or management of prediabetes.

Insulin secretion and action with increasing age - A comparison between Middle Eastern immigrants and native Swedes

Aims

Little is known how insulin secretion and action change over time in populations of different ethnicities. We studied changes in insulin secretion and action with increasing age in Iraqi-born immigrants and native Swedes, and investigated if the changes were modified by region of origin.

Methods

Residents of Malmö, 30–75 years of age born in Iraq or Sweden, were invited to participate in this population-based, cross-sectional study. Health examination, medical history, lifestyle, sociodemographic data, and fasting blood samples were assessed. Oral glucose tolerance tests were performed and insulin secretion (disposition index, DIo) and insulin sensitivity index (ISI) calculated using the Matsuda indices.

Results

In total 1881 people participated; 1193 Iraqi- and 688 Swedish born. DIo decreased with increasing age in the total study population (β for the effect of age on ln DIo: ^-0.018, 95% CI ^-0.023 to ^-0.013, P < 0.001), adjusted for origin, lifestyle and anthropometric measures. DIo was generally lower in Iraqis vs. Swedes (median: 12,712.9 vs. 14,659.2, P = 0.004), but the difference disappeared when adjusted for BMI.

Further, ISI declined with increasing age in both Iraqis and Swedes. ISI was generally lower among Iraqis compared to Swedes, (median: 76.9 vs. 102.3, p < .001). The difference could not be fully explained by age, sex, lifestyle, and anthropometric measures. No significant interactions were observed.

Conclusions

The levels of DIo and ISI were lower among Iraqis compared to Swedes and declined with increasing age, irrespective of origin.

Thyroid-Stimulating Hormone and Thyroid Hormones and Incidence of Diabetes: Prospective Results of the Brazilian Longitudinal Study of Adult Health (ELSA-BRASIL)

Background: There are conflicting data regarding the association of thyroid function with incident diabetes. We prospectively investigated thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and its conversion ratio (fT3:fT4) with the risk of developing diabetes in euthyroid subjects and those with subclinical thyroid dysfunction. Our hypothesis is that this relationship is a U-shaped curve since both subclinical thyroid diseases may be associated with diabetes. Methods: ELSA-Brasil is a highly admixed cohort study of 35-74 years old at baseline (2008-2010). Levels of TSH, fT4, fT3, and fT3:fT4 ratio were evaluated at baseline and incident diabetes was estimated over an 8.2-year follow-up (2017-2019). Diabetes was identified based on medical diagnosis, prescriptions, and laboratory tests. The risk of diabetes was evaluated according to quintiles of TSH, fT4, fT3, and fT3:fT4 ratio using Poisson regression with robust variance presented as relative risk (RR) with confidence interval [CI] of 95% after multivariable adjustment for sociodemographic and cardiovascular risk factors (reference third quintile), and as continuous variables. Results: We included 7948 participants (mean age, 50.2 [standard deviation 8.6] years; 54.4% female): 7177 euthyroid, 726 with subclinical hypothyroidism, and 45 with subclinical hyperthyroidism. Incidence of diabetes was 14.8%. No association was found for TSH, fT4, fT3, and fT3:fT4 ratio quintiles with incident diabetes. Using continuous variables, the increase of 1-unit (1-U) of fT4 decreased the risk of diabetes (RR 0.94 [CI 0.91-0.99]), while the increase of 1-U of the fT3:fT4 ratio increased the diabetes risk (RR 1.37 [CI 1.15-1.63]). The increase of 1-U of fT3 was associated with an increased risk of diabetes, but without significance after multivariable adjustment. In body mass index-stratified analysis, people with overweight or obesity presented a modest significantly higher risk of diabetes in the lowest quintile of fT4 (RR 1.04 [CI 1.01-1.07]) and an inverse association with incident diabetes in the first quintile of fT3:fT4 ratio (RR, 0.95 [CI 0.93-0.98]). The analyses using continuous variables presented similar findings. Conclusion: These findings suggest that fT4 and fT3 levels and the conversion rate might be additional risk factors associated with incident diabetes, especially in the presence of overweight or obesity. However, they need to be confirmed in future studies. (ClinicalTrials.gov Identifier: NCT02320461).

Dietary and lifestyle indices for hyperinsulinemia with the risk of obesity phenotypes: a prospective cohort study among Iranian adult population

BACKGROUND

Previous studies have cited insulin-related disorders, including hyperinsulinemia, as one of the main causes of obesity risk and metabolic disorders. We aimed to investigate the association of the Empirical Dietary Index for Hyperinsulinemia (EDIH) and Empirical Lifestyle Index for Hyperinsulinemia (ELIH) with the risk of obesity phenotypes among Iranian adults.

METHODS

Present study was conducted on 2705 subjects, including 1604 metabolically healthy normal weights (MHNW) and 1101 metabolically healthy obesity (MHO) individuals. Obesity phenotypes, including MHNW, MHO, metabolically unhealthy normal weights (MUNW), and metabolic unhealthy obesity (MUO), were determined using the criteria of the Joint International statement (JIS) for metabolic syndrome. Dietary intake data from the previous year was gathered using a food frequency questionnaire. Cox proportional hazard regression was used to estimate the hazard ratio and 95% confidence intervals (HRs and 95% CIs) of obesity phenotypes incident across tertiles of EDIH and ELIH scores.

RESULTS

The mean ± SD of age and BMI of all participants were 33.5 ± 12.2 years and 24.3 ± 3.8 kg/m2, respectively. In the multivariable-adjusted model, a higher ELIH score was associated with a greater risk for incidence of MUO (HR: 3.47, 95%CI: 2.54-4.74; Ptrend =  < 0.001) and MHO (HR: 3.61, 95%CI: 2.73-4.77; Ptrend =  < 0.001). Also, a higher score of EDIH was related to an increased risk of MUO incidence (HR: 1.35, 95%CI: 1.02-1.79; P for trend = 0.046). However, there was no significant association between a higher score of EDIH and the risk of MHO.

CONCLUSION

Our findings revealed that a high insulinemic potential of diet and lifestyle, determined by EDIH and ELIH indices, may be related to an increase in the simultaneous occurrence of obesity with metabolic disorders in Iranian adults.

Dynamic assessment of insulin secretion and insulin resistance in Asians with prediabetes

AIMS/HYPOTHESIS

Prediabetes and type 2 diabetes are highly prevalent in Asia. Understanding the pathophysiology of abnormal glucose homeostasis in Asians will have important implications for reducing disease burden, but there have been conflicting reports on the relative contributions of insulin secretion and action in disease progression. In this study, we aimed to assess the contribution of β-cell dysfunction and insulin resistance in the Asian prediabetes phenotype.

METHODS

We recruited 1679 Asians with prediabetes (n = 659) or normoglycemia (n = 1020) from a multi-ethnic population in Singapore. Participants underwent an oral glucose tolerance test, an intravenous glucose challenge, and a hyperinsulinemic-euglycemic clamp procedure to determine glucose tolerance, β-cell responsivity, insulin secretion, insulin clearance and insulin sensitivity.

RESULTS

Participants with prediabetes had significantly higher glucose concentrations in the fasting state and after glucose ingestion than did normoglycemic participants. Insulin sensitivity (M/I ratio) was ~15% lower, acute insulin response (AIR) to intravenous glucose and β-cell responsivity to oral glucose were ~35% lower, but total insulin secretion rate in the fasting state and after glucose ingestion was ~10% greater in prediabetic than in normoglycemic participants. The decrease in β-cell function with worsening glucose homeostasis in Asians with prediabetes was associated with progressively greater defects in AIR rather than M/I. However, analysis using static surrogate measures (HOMA indices) of insulin resistance and β-cell function revealed a different pattern.

CONCLUSIONS

Lower AIR to intravenous glucose and β-cell responsivity to oral glucose, on a background of mild insulin resistance, are the major contributors to the dysregulation of glucose homeostasis in Asians with prediabetes.

Development and validation of dietary and lifestyle insulinemic indices among Iranian adult population

BACKGROUND

There is no study regarding developing a valid index to predict insulin-related disorders in the Iranian population based on their dietary habits and lifestyle. In the current study, we aimed to develop and validate insulinemic potential indices of diet and lifestyle in Iranian adults.

METHODS

In this cross-sectional study, we analysed data of 1063 men and women aged ≥ 25 years among participants of the examination three of Tehran lipid and glucose study (TLGS) (2006-2008). Dietary intakes were assessed using a valid semi-quantitative food frequency questionnaire. Dietary and lifestyle indices were developed using stepwise linear regression analysis based on dietary intakes, body mass index, and physical activity data. Fasting serum insulin concentration and homeostatic model assessment for insulin resistance (HOMA-IR) were used as biomarkers of hyperinsulinemia (HI) and insulin resistance (IR). Validation analyses were performed in examination four of TLGS.

RESULTS

We developed four indices related to insulin homeostasis, including the dietary index for HI (DIH), the dietary index for IR (DIR), the lifestyle index for HI (LIH), and the lifestyle index for IR (LIR). Based on multivariable-adjusted models, the relative values of the biomarker in subjects in the highest quartile of indices were 45% for LIH (95% CI 1.36-1.55, P_trend < 0.001), 28% for DIR (95% CI 1.13-1.42, P_trend = 0.019), and 51% for LIR (95% CI 1.41-1.61, P_trend < 0.001), higher than those in the reference quartile, respectively.

CONCLUSION

We designed and validated indices to determine the insulin potential of diet and lifestyle for the Iranian population, according to Iran's demographic and dietary intake characteristics.

Prediction of insulin treatment in women with gestational diabetes mellitus

INTRODUCTION

The identification of pregnant women with Gestational Diabetes Mellitus (GDM) who will require insulin therapy, may modify their management to closer monitoring and probable early interventions. The aim of the study was to develop a predictive model for the necessity of insulin treatment in women with GDM.

MATERIALS AND METHODS

This was a prospective cohort study. Data from 775 women diagnosed with GDM per the IADPSG criteria were analyzed using logistic regression and a machine learning algorithm, the Classification and Regression Trees (CART). Potential predictors routinely recorded at follow-up visits were tested and used for the development of the model. The resultant model was externally validated using the data from two different perinatology clinics.

RESULTS

Preconceptional maternal BMI and morning fasting blood glucose levels at baseline and at 1 h during an Oral Glucose Tolerance Test (OGTT) were independent significant predictors for the treatment modality of GDM. Baseline blood glucose greater than 98 mg/dl and preconceptional maternal Body Mass Index (BMI) between 26 and 31 kg/height2 increased substantially the probability of insulin therapy (odds ratio [OR] 4.04, 95% confidence interval [CI] CI 2.65-6.17 and 2.21, 95%CI 1.42-3.43, respectively). The area under the curve (AUC) for the internal and external validation of the predictive model was 0.74 and 0.77, respectively.

CONCLUSIONS

A simple model based on maternal characteristics and the values of an OGTT can predict the need for insulin treatment with accuracy. Overweight women with an abnormal baseline blood glucose at OGTT are at high likelihood for insulin treatment.

KEY MESSAGE

Fifteen to 30% of women with Gestational Diabetes Mellitus (GDM) require insulin therapy. Overweight women with baseline blood glucose greater than 98 mg/dl at OGTT are at increased risk for insulin treatment and close monitoring and increased physical exercise are required.

The association of insulinemic potential of diet and lifestyle with the risk of insulin-related disorders: a prospective cohort study among participants of Tehran Lipid and Glucose Study

BACKGROUND

We aim to assess the association of empirical dietary (EDIH) and lifestyle (ELIH) index for hyperinsulinemia with the risk of insulin resistance, hyperinsulinemia, insulin sensitivity, and β-cell dysfunction in Iranian adults.

METHODS

In this prospective study, a total of 1244 men and women aged ≥ 20 years were selected among participants of the Tehran lipid and glucose study and followed for 3.2 years. Dietary intakes were assessed using a valid semi-quantitative food frequency questionnaire. Dietary and lifestyle insulinemic potential indices were calculated using dietary intake, body mass index, and physical activity information. Multivariable logistic regression was used to estimate the associated risk of a 3-year incidence of insulin-related disorders.

RESULTS

The mean ± SD age and BMI of all eligible participants (42.7% males) were 43.0 ± 13.0 and 27.4 ± 4.9 in the study's baseline. After adjusting for all potential confounders, participants in the highest tertile of ELIH score had a greater risk of developing hyperinsulinemia (OR:2.42, 95%CI:1.52-3.86, P for trend =  < 0.001), insulin resistance (OR:2.71, 95%CI:1.75-4.18, P for trend =  < 0.001) and insulin insensitivity (OR:2.65, 95%CI: 1.72-4.10, P for trend =  < 0.001) compared with those in the lowest tertile. However, the risk of incident β-cell dysfunction was lower in individuals with a higher score of ELIH in comparison to those with the lowest score (OR:0.30, 95%CI:0.19-0.45, P for trend =  < 0.001).

CONCLUSIONS

Empirical lifestyle index for hyperinsulinemia was directly associated with insulin resistance, insulin insensitivity, and hyperinsulinemia and was inversely associated with β-cells dysfunction.

Association of TG/HDLC ratio trajectory and risk of type 2 diabetes: A retrospective cohort study in China

BACKGROUND

The association of ratio of triglycerides to high-density lipoprotein cholesterol (TG/HDL-C ratio) change trajectory with risk of type 2 diabetes mellitus (T2DM) remains unknown. The aim of this study was to evaluate the association between risk of T2DM and TG/HDL-C ratio change trajectory.

METHODS

A total of 18 444 participants aged 18-80 years old were included in this cohort study. Linear regression and quadratic regression models were used to determine the TG/HDL-C ratio change trajectory. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between TG/HDL-C ratio change trajectory and probability of T2DM.

RESULTS

T2DM developed in 714 participants during a median follow-up of 5.74 years (92 076.23 person-years of follow-up). After adjusting for baseline potential confounders, odds of T2DM were greater for participants with the increasing, U-shape, bell-shape, and other shape change vs decreasing change (adjusted OR [aOR] 2.01, 95% CI 1.42-2.81; 1.56, 1.15-2.13; 1.60, 1.17-2.20; and 1.49, 1.13-2.00, respectively). The results were robust in the sensitivity analyses on excluding baseline participants with T2DM. Moreover, the associations remained significant with male sex, age <60 years and body mass index <24 kg/m2 .

CONCLUSIONS

This retrospective study revealed increased probability of T2DM with increasing, U-shape, bell-shape, and other-shape TG/HDL-C ratio change trajectories, especially with male sex, age <60 years and body mass index <24 kg/m2 .

Insulinemic Potential of Lifestyle Is Inversely Associated with Leukocyte Mitochondrial DNA Copy Number in US White Adults

BACKGROUND

Poor lifestyles have been linked to insulin insensitivity/hyperinsulinemia, which may contribute to downstream changes such as inflammation and oxidative damage and the development of chronic diseases. As a biomarker of intracellular oxidative stress, leukocyte mitochondrial DNA copy number (mtDNA-CN) has been related to lifestyle factors including diet and weight. No epidemiologic study has examined the relation between combined insulinemic potential of lifestyle and mtDNA-CN.

OBJECTIVES

Our aim was to examine the association between Empirical Lifestyle Index for Hyperinsulinemia (ELIH) and leukocyte mtDNA-CN in US men and women.

METHODS

This cross-sectional analysis included 2835 white adults without cancers, diabetes, or cardiovascular disease at blood collection, including 2160 women from the Nurses' Health Study and 675 men from the Health Professionals Follow-Up Study. ELIH is an index based on plasma C-peptide that characterizes the insulinemic potential of lifestyle (diet, body weight, and physical activity). Relative mtDNA-CN in peripheral blood leukocytes was measured by qPCR-based assay.

RESULTS

We found a significant inverse association between ELIH and mtDNA-CN. In multivariable-adjusted linear models, absolute least squares means ± SDs of mtDNA-CN z score across ELIH quintiles in women were as follows: Q1: 0.14 ± 0.05; Q2: 0.04 ± 0.06; Q3: 0.008 ± 0.05; Q4: 0.01 ± 0.05; and Q5: -0.06 ± 0.05 (P-trend = 0.006). Means ± SDs in men were as follows: Q1: 0.25 ± 0.09; Q2: 0.23 ± 0.09; Q3: 0.07 ± 0.09; Q4: 0.02 ± 0.09; and Q5: -0.04 ± 0.09 (P-trend = 0.007). Means ± SDs in all participants were as follows: Q1: 0.16 ± 0.05; Q2: 0.07 ± 0.05; Q3: 0.01 ± 0.05; Q4: 0.01 ± 0.05; and Q5: -0.05 ± 0.05 (P-trend = 0.0004).

CONCLUSIONS

Hyperinsulinemic lifestyles (i.e., higher ELIH) were associated with lower leukocyte mtDNA-CN among subjects without major diseases, suggesting that the difference in lifestyle insulinemic potential may be related to excessive oxidative stress damage.

Early development of decreased β-cell insulin secretion in children and adolescents with hemoglobin H disease and its relationship with levels of anemia

BACKGROUND

Diabetes mellitus (DM) associated with iron overload has been reported among adults with transfusion-dependent thalassemia and those with non-transfusion-dependent thalassemia (NTDT), especially in β-thalassemia disease. However, little is known about glucose metabolism and how early its dysregulation can develop in α-thalassemia hemoglobin H (Hb H) disease, which is one of the most common types of NTDT worldwide.

PROCEDURE

We prospectively calculated glucose metabolism index in 40 patients (aged 10-25 years) with Hb H disease. Glucose metabolism data were compared between patients with deletional versus nondeletional Hb H, and between patients with normal versus abnormal insulin secretion/sensitivity.

RESULTS

Despite normal glucose tolerance in all patients, 52.5% had abnormal insulinogenic index indicating decreased β-cell insulin secretion. Patients with functional hemoglobin < 8 g/dL had significantly higher percentages of abnormal insulinogenic index. There was no significant difference in abnormal insulinogenic index between deletional and nondeletional Hb H.

CONCLUSION

Decreased β-cell insulin secretion is highly prevalent among children and adolescents with Hb H disease, and it is associated with levels of functional anemia at baseline, but not with the type of Hb H disease. This result warrants heightened awareness among hematologists due to potentially increased risk of DM later in life.

Fasting Blood Glucose Predicts Incidence of Hypertension Independent of HbA1c Levels and Insulin Resistance in Middle-Aged Japanese: The Saku Study

BACKGROUND

Relationships between blood glucose (BG) levels and insulin action, and incidence of hypertension have not been well known epidemiologically. This study aimed to investigate the association between indices of diabetes and the incidence of hypertension and compare the predictive powers of these indices in middle-aged Japanese.

METHODS

This 5-year cohort study included 2,210 Japanese aged 30-64 years without hypertension. Hazard ratios of high fasting blood glucose (FBG) levels, high post-loaded BG levels, high glycated hemoglobin (HbA1c) levels, insulin resistance (defined by homeostasis model assessment of insulin resistance [HOMA-IR]) and impaired insulin secretion at baseline for the incidence of hypertension were estimated using multivariable-adjusted Cox proportional hazard models. Hypertension was defined as blood pressure ≥ 140/90 mm Hg or receiving antihypertensive treatment.

RESULTS

During the follow-up, 456 participants developed hypertension. After adjustment for HbA1c and HOMA-IR, FBG was independently and significantly associated with hypertension. The hazard ratio of participants with FBG ≥ 7.0 mmol/l was 1.79 compared with those with FBG < 5.6 mmol/l. Even among those with HbA1c < 6.5%, HOMA-IR < 2.5, body mass index < 25 kg/m2, age < 55 years old, blood pressure < 130/80 mm Hg or non- and moderate drinking, the results were similar. High 120-minute BG level and impaired insulin secretion did not increase the risk for hypertension.

CONCLUSIONS

FBG was a predictable index for future incidence of hypertension in middle-aged Japanese men and women. This is the first study comparing predictive powers of indices of diabetes for the incidence of hypertension.

Antizyme inhibitor 1 genetic polymorphisms associated with diabetic patients validated in the livers of diabetic mice

Diabetes mellitus (DM) is a complex disease caused by absolute or relative insulin deficiency. The C57BLKsJ-db/db mouse model is a useful animal model for studying type 2 DM (T2DM). The present study investigated the association between an antizyme inhibitor 1 (AZIN1) gene polymorphism (rs1062048) and T2DM susceptibility in 2,270 Taiwanese individuals (570 patients with T2DM and 1,700 controls). Additionally, the present study investigated AZIN1 gene and protein expression in the liver tissues of mice in three age groups (4, 16 and 32 weeks) through reverse transcription-quantitative PCR, western blotting and immunohistochemistry. The data indicated that the genotype frequency distribution of the rs1062048 single-nucleotide polymorphism differed significantly between the patients with T2DM and controls (P<0.05). Furthermore, gene and protein expression levels of AZIN1 were significantly lower in early stage and late stage T2DM mouse liver samples than in control samples. Overall, the data suggested that AZIN1 expression is involved in T2DM development.

The association between glycemic control and lung function impairment in individuals with diabetes: the Saku study

Aim

Though diabetes is a risk factor for lung function impairment, whether the glycemic control level affects lung function in individuals with diabetes remains unclear. The present study aimed to assess the association between glycemic control level and restrictive or obstructive lung function impairment in individuals with diabetes.

Methods

This cross-sectional study included 1028 individuals with diabetes, aged 40-69 years, who underwent a medical checkup between April 2008 and March 2014. Hemoglobin A1c (HbA1c) was categorized as  < 6.9%, 7.0-7.9%, and  ≥ 8.0%. Restrictive and obstructive lung function impairment was defined by a forced vital capacity (FVC) < 80% predicted and a forced expiratory volume in 1 s to FVC ratio < 0.70.

Results

Of the participants, 8.7% and 6.3% were classified as having restrictive and obstructive lung function impairment, respectively. The multivariable-adjusted odds ratios and 95% confidence intervals for restrictive lung function impairment were 1.43 (0.84-2.42) in individuals with HbA1c 7.0-7.9%, and 2.42 (1.38-4.26) in individuals with HbA1c ≥ 8.0%, compared with those who had HbA1c < 6.9% (p for trend = 0.002). In contrast, glycemic control level was not associated with obstructive lung function impairment (p for trend = 0.749).

Conclusions

Poor glycemic control was associated with restrictive lung function impairment in individuals with diabetes. Good glycemic control would be important to minimize restrictive lung function impairment in individuals with diabetes.

Risk of developing type 2 diabetes according to blood pressure levels and presence or absence of hypertensive treatment: the Saku study

The aim was to investigate the risk of developing type 2 diabetes according to blood pressure (BP) levels and presence or absence of hypertensive treatment. This 5-year cohort study comprised 3508 Japanese adults aged 30-74 years without diabetes who had undergone a medical checkup including a 75-g oral glucose tolerance test (OGTT) between April 2008 and March 2009 at Saku Central Hospital. Participants receiving antihypertensive treatment were categorized into controlled hypertension ( < 140/90 mmHg) or uncontrolled hypertension ( ≥ 140/90 mmHg) groups. Participants not receiving antihypertensive treatment were categorized: optimal BP ( < 120/80 mmHg), normal BP (120-129/80-84 mmHg), high-normal BP (130-139/85-89 mmHg), grade I hypertension (140-159/90-99 mmHg), and grade II/III hypertension ( ≥ 160/100 mmHg). Hazard ratios and 95% confidence intervals for the incidence of type 2 diabetes as defined by the 75-g OGTT were estimated using multivariable-adjusted Cox proportional hazard models in reference to optimal BP. During an average of 4.4 years of follow-up, 295 participants developed type 2 diabetes. Those with high-normal BP, grade I hypertension, grade II/III hypertension, and uncontrolled hypertension were at significantly higher risk for developing type 2 diabetes, with hazard ratios (95% confidence intervals) of 1.53 (1.03-2.29), 1.53 (1.02-2.32), 2.19 (1.01-4.77), and 1.81 (1.10-2.99), respectively. In conclusion, compared with those with optimal BP, individuals with BP ≥ 130/85 mmHg not receiving antihypertensive treatment and uncontrolled hypertensives with BP ≥ 140/90 mmHg receiving antihypertensive treatment were at a significantly higher risk for developing type 2 diabetes.

Objectively-Assessed Patterns and Reported Domains of Sedentary Behavior Among Japanese Older Adults

BACKGROUND

Prolonged periods of sitting time can be adversely associated with older adults' well-being and functional capacities. Understanding patterns and contexts of sedentary behaviors (SB) can inform approaches to prevention. This study examined Japanese older adults' objectively-assessed patterns and reported domains of SB and their interrelationships.

METHODS

Participants (n = 297; aged 65-84 years) of this cross-sectional study wore an accelerometer for 7 days and completed a survey. Five measures related to SB patterns were identified from the accelerometer data. SB from six domains, socio-demographics, and chronic conditions were identified from the survey data. Relative contributions of six domains to objectively-measured prolonged sedentary time (≥30 minutes) and the number of breaks were examined in a series of multivariate linear regressions. Covariates were socio-demographics, chronic conditions, and accelerometer wear time.

RESULTS

On average, participants spent 8.8 hours a day sedentary (58% of accelerometer wear time), with 7.6 breaks per sedentary hour, and 3.7 hours a day through prolonged sedentary bouts (4.4 time/day). The proportions of time in the SB domains were 9.4% for car, 4.0% for public transport, 6.1% for work, 45.5% for television (TV) viewing, 9.8% for computer use, and 25.1% for other leisure. Domains of SB that contributed significantly to longer sedentary time through prolonged bouts were TV viewing and computer use. TV viewing was also associated with a lesser number of breaks.

CONCLUSIONS

For Japanese older adults, initiatives to address SB could focus on breaking-up prolonged periods of SB by encouraging more frequent breaks, especially during TV viewing.

Diabetes Among Non-Overweight Individuals: an Emerging Public Health Challenge

PURPOSE OF REVIEW

Overweight and obesity are well-established risk factors for type 2 diabetes. However, a substantial number of individuals develop the disease at underweight or normal weight. In this review, we discuss the epidemiology of type 2 diabetes in non-overweight adults; pose questions about etiology, pathophysiology, diagnosis, and prognosis; and examine implications for prevention and treatment.

RECENT FINDINGS

In population-based studies, the prevalence of type 2 diabetes ranged from 1.4-10.9%. However, the prevalence of type 2 diabetes in individuals with BMI < 25 kg/m² ranged from 1.4-8.8%. In countries from Asia and Africa, the proportion of individuals with diabetes who were underweight or normal weight ranged from 24 to 66%, which is considerably higher than the US proportion of 10%. Impairments in insulin secretion, in utero undernutrition, and epigenetic alterations to the genome may play a role in diabetes development in this subgroup. A substantial number of individuals with type 2 diabetes, particularly those with recent ancestry from Asia or Africa, are underweight or normal weight. Future research should consist of comprehensive studies of the prevalence of type 2 diabetes in non-overweight individuals; studies aimed at understanding gaps in the mechanisms, etiology, and pathophysiology of diabetes development in underweight or normal weight individuals; and trials assessing the effectiveness of interventions in this population.

A prospective study of the impact of diabetes mellitus on restrictive and obstructive lung function impairment: The Saku study

BACKGROUND

To assess the impact of diabetes on restrictive and obstructive lung function impairment.

METHODS

This 5-year prospective study included 7524 participants aged 40-69years without lung function impairment at baseline who underwent a comprehensive medical check-up between April 2008 and March 2009 at Saku Central Hospital. Diabetes was defined by fasting plasma glucose ≥7.0mmol/l (126mg/dl), HbA1c≥6.5% (48mmol/mol), or a history of diabetes, as determined by interviews conducted by the physicians. Restrictive and obstructive lung function impairment were defined as forced vital capacity (FVC) <80% predicted and forced expiratory volume in 1s (FEV₁) to FVC ratio (FEV₁/FVC) <0.70, respectively. Participants were screened until they developed restrictive or obstructive lung function impairment or until March 2014.

RESULTS

During the follow-up period, 171 and 639 individuals developed restrictive and obstructive lung function impairment, respectively. Individuals with diabetes had a 1.6-fold higher risk of restrictive lung function impairment than those without diabetes after adjusting for sex, age, height, abdominal obesity, smoking status, exercise habits, systolic blood pressure, HDL-cholesterol, log-transformed high-sensitivity C-reactive protein, and baseline lung function [multivariable-adjusted HR and 95% CI; 1.57 (1.04-2.36)]. In contrast, individuals with diabetes did not have a significantly higher risk of obstructive lung function impairment [multivariable-adjusted HR and 95% CI; 0.93 (0.72-1.21)].

CONCLUSION

Diabetes was associated with restrictive lung function impairment but not obstructive lung function impairment.

Association between alcohol consumption and incidence of impaired insulin secretion and insulin resistance in Japanese: The Saku study

AIMS

To investigate the effect of alcohol consumption on impaired insulin secretion and insulin resistance in Japanese.

METHODS

The participants in this 5-year cohort study were 2100 Japanese aged 30-74 years without type 2 diabetes mellitus, impaired insulin secretion, or insulin resistance who underwent a medical checkup including 75-g OGTT between April 2008 and March 2009 at Saku Central Hospital. Alcohol consumption was categorized as follows: non-drinker (0 g/week), light drinker (1-139 g/week in men and 1-69 g/week in women), moderate drinker (140-274 g/week in men and 70-139 g/week in women) and heavy drinker (≥275 g/week in men and ≥140 g/week in women). The hazard ratios (HRs) and 95% CIs among light to heavy drinkers for incidence of impaired insulin secretion (insulinogenic index ≤51.7) and insulin resistance (HOMA-IR ≥ 2.5), detected by an OGTT at the time of a follow-up medical checkup before the end of March 2014, were estimated by multivariable adjusted Cox proportional hazard models as reference values for non-drinkers.

RESULTS

There were 708 cases of impaired insulin secretion and 191 cases of insulin resistance. The HRs (95% CIs) for impaired insulin secretion in light, moderate and heavy drinkers were 1.16 (0.96-1.40), 1.35 (1.07-1.70) and 1.64 (1.24-2.16), respectively (P for trend <0.001). For insulin resistance, the HRs were 1.22 (0.84-1.76), 1.42 (0.91-2.22) and 1.59 (0.96-2.65), respectively (P for trend = 0.044).

CONCLUSION

Alcohol consumption was positively associated with the incidence of both impaired insulin secretion and insulin resistance.

Ethnic Similarities and Differences in the Relationship between Beta Cell Mass and Diabetes

Recent evidence has revealed that a change of functional beta cell mass is an essential factor of the pathophysiology of type 2 diabetes (T2DM). Since beta cell dysfunction is not only present in T2DM but also progressively worsens with disease duration, to preserve or recover functional beta cell mass is important in both prevention of the development of T2DM and therapeutic strategies for T2DM. Furthermore, ethnic difference in functional beta cell mass may also need to be taken into account. Recent evidences suggest that Asians have less beta cell functional capacity compared with Caucasians. Preservation or recovery of functional beta cell mass seems to be further emphasized for Asians because of the limited capacity of beta cell. This review summarizes the current knowledge on beta cell dysfunction in T2DM and discusses the similarities and differences in functional beta cell mass between ethnicities in the face of obesity and T2DM.

Body mass index trajectory patterns and changes in visceral fat and glucose metabolism before the onset of type 2 diabetes

We investigated BMI trajectory patterns before diabetes diagnosis and examined associated changes in visceral adiposity and glucose metabolism. 23,978 non-diabetic Japanese participants (2,789 women) aged 30–64 years were assessed with a mean follow-up of 7.6 years. Diabetes was diagnosed via fasting glucose, HbA_1c, and self-report. Latent-class trajectory analyses were performed to identify BMI trajectories. Longitudinal changes in BMI, visceral adiposity, and glucose metabolism were estimated using mixed models. 1,892 individuals developed diabetes. Three distinct BMI trajectories were identified in adults developing and not developing diabetes, respectively. Among adults developing diabetes, 47.3% were classified as “medium BMI” (n = 895), and had increased mean BMI within the obesity category before diagnosis. The “low BMI” group (38.4%, n = 726) had an initial mean BMI of 21.9 kg/m², and demonstrated small weight gain. The “high BMI” group (n = 271) were severely obese and showed greater increase in BMI until diagnosis. All groups which developed diabetes showed absolute and/or relative increase in visceral fat and impaired β-cell compensation for insulin resistance. All groups not developing diabetes showed measured variables were relatively stable during observation. These data suggest that visceral fat gain may induce β-cell failure in compensation for insulin resistance, resulting in diabetes regardless of obesity level.

Impact of metabolic syndrome on the incidence of type 2 diabetes in middle-aged Japanese individuals with impaired insulin secretion: the Saku study

AIMS

To assess the impact of metabolic syndrome (MetS) on the incidence of type 2 diabetes in middle-aged Japanese individuals with impaired insulin secretion (IIS).

METHODS

This cohort study included 1,702 individuals aged 40-59 without diabetes at baseline who underwent a comprehensive medical check-up between April 2008 and March 2009 at Saku Central Hospital. Participants were classified according to their IIS and insulin resistance (IR) status [normal, isolated IR (i-IR), or isolated IIS (i-IIS)] and MetS (presence or absence). They were followed up until March 2014. Type 2 diabetes was defined based on fasting and 2-h post-load plasma glucose concentrations and by the receipt of medical treatment for diabetes.

RESULTS

During 7,572 person-years of follow-up, 92 individuals developed type 2 diabetes. The incidence rates (/1,000 person-years) for type 2 diabetes in the normal without MetS, normal with MetS, i-IR without MetS, i-IR with MetS, i-IIS without MetS, and i-IIS with MetS groups were 5.3, 3.7, 11.3, 24.7, 16.7, and 59.5, respectively. The multivariable-adjusted hazard ratios (HRs) and 95 % confidence intervals (CIs) for type 2 diabetes in the normal with MetS, i-IR with MetS, and i-IIS with MetS groups, relative to the normal without MetS group, were 0.52 (0.12-2.25), 3.78 (1.93-7.42), and 7.94 (3.96-15.91), respectively. Additionally, a positive association of MetS with type 2 diabetes was observed in the i-IIS group [HR (95 % CI) 3.56 (1.88-6.73)] but not in the normal and i-IR groups.

CONCLUSIONS

The prevention of MetS is important, particularly in individuals with low insulin secretion.

Sex-specific incidence rates and risk factors of insulin resistance and β-cell dysfunction: a decade follow-up in a Middle Eastern population

AIMS

To examine the incidence of and risk factors for insulin resistance and β-cell dysfunction in a representative Iranian population over a median follow-up of 9.2 years.

METHODS

In total, 3662 people (1528 men) without known diabetes with a baseline homeostasis model assessment of insulin resistance (HOMA-IR) level < 75th percentile and, when β-cell dysfunction was the outcome of interest, 3664 people (1530 men) with a homeostasis model assessment of β-cell function (HOMA-β) level ≥ 25th percentile were included in the study (HOMA-IR < 2.20 and HOMA-β ≥ 64.3 among men, and HOMA-IR < 2.39 and HOMA-β ≥ 81.7 among women).

RESULTS

The incidence rates of insulin resistance and β-cell dysfunction were 56.3 and 33.6/1000 person-years among men and 48.6 and 50.3/1000 person-years among women, respectively. Applying multivariable Cox regression in both sexes, fasting insulin, triglyceride/HDL cholesterol ratio and lower education were positive predictors of insulin resistance, whereas age was a negative predictor. Moreover, fasting plasma glucose, waist-to-height ratio, wrist circumference and lower hip circumference were significantly associated with incident insulin resistance only among women (all P < 0.05). Considering β-cell dysfunction in both sexes, age and fasting plasma glucose increased the risk, whereas 2-h post-challenge plasma glucose was a positive predictor only among men, and waist-to-height ratio and triglyceride/HDL cholesterol ratio were negative predictors only among women (all P < 0.05).

CONCLUSIONS

Modifiable risk factors are related to the incidence of insulin resistance and β-cell dysfunction, which can be prevented with proper strategies although the difference between men and women should be taken into account.

Development and validation of empirical indices to assess the insulinaemic potential of diet and lifestyle

The glycaemic and insulin indices assess postprandial glycaemic and insulin response to foods, respectively, which may not reflect the long-term effects of diet on insulin response. We developed and evaluated the validity of four empirical indices to assess the insulinaemic potential of usual diets and lifestyles, using dietary, lifestyle and biomarker data from the Nurses' Health Study (NHS, n 5812 for hyperinsulinaemia, n 3929 for insulin resistance). The four indices were as follows: the empirical dietary index for hyperinsulinaemia (EDIH) and the empirical lifestyle index for hyperinsulinaemia (ELIH); the empirical dietary index for insulin resistance (EDIR) and the empirical lifestyle index for insulin resistance (ELIR). We entered thirty-nine FFQ-derived food groups in stepwise linear regression models, and defined indices as patterns most predictive of fasting plasma C-peptide, for the hyperinsulinaemia pathway (EDIH and ELIH), and of theTAG:HDL-cholesterol ratio, for the insulin-resistance pathway (EDIR and ELIR). We evaluated the validity of indices in two independent samples from NHS-II and Health Professionals Follow-up Study (HPFS) using multivariable-adjusted linear regression analyses to calculate relative concentrations of biomarkers. The EDIH is comprised of eighteen food groups; thirteen were positively associated with C-peptide and five were inversely associated. The EDIR is comprised of eighteen food groups; ten were positively associated with TAG:HDL-cholesterol and eight were inversely associated. Lifestyle indices had fewer dietary components, and included BMI and physical activity as components. In the validation samples, all indices significantly predicted biomarker concentrations - for example, the relative concentrations of the corresponding biomarkers comparing extreme index quintiles in the HPFS were EDIH, 1·29 (95 % CI 1·22, 1·37); ELIH, 1·78 (95 % CI 1·68, 1·88); EDIR, 1·44 (95 % CI 1·34, 1·55); and ELIR, 2·03 (95 % CI 1·89, 2·19); all P trend<0·0001. The robust associations of these novel hypothesis-driven indices with insulin response biomarker concentrations suggest their usefulness in assessing the ability of whole diets and lifestyles to stimulate and/or sustain insulin secretion.

Risk of proteinuria among individuals with persistent borderline diabetes: the Saku study

OBJECTIVE

To investigate the risk of decreased estimated glomerular filtration rate (eGFR) and proteinuria among individuals with borderline diabetes.

METHODS

This 5-year cohort study involved 2849 participants aged 30-79 years without diabetes or chronic kidney disease at baseline (April 2008-March 2009). Participants were categorized into two groups-normoglycemia and borderline diabetes-based on the results of a 75-g oral glucose tolerance test at baseline. Participants underwent annual comprehensive medical check-ups during the follow-up period until March 2014. Main outcomes were defined as proteinuria ≥[1+] or eGFR <60 ml/min/1.73 m2. Cox proportional hazards regression was used to estimate the hazard ratio (HR) and 95 % confidence interval (CI) of eGFR <60 ml/min/1.73 m2 and proteinuria ≥[1+] for the borderline diabetes group compared with the normoglycemia group.

RESULTS

During the follow-up period, 335 individuals developed eGFR <60 ml/min/1.73 m2 and 136 individuals developed proteinuria ≥[1+]. Participants in the borderline diabetes group did not have a significantly higher risk of eGFR <60 ml/min/1.73 m2 or proteinuria ≥[1+] after multivariable adjustment. However, participants with borderline diabetes who were also diagnosed with borderline diabetes at the endpoint examination had a significantly higher risk of proteinuria ≥[1+] compared with participants with normoglycemia who also had normoglycemia at the endpoint examination; the HR (95 % CI) was 1.76 (1.11-2.78).

CONCLUSIONS

Persistent borderline diabetes significantly increases the risk of proteinuria.