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

Assessing body composition through anthropometry: Implications for diagnosing and managing polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is a multifaceted endocrine disorder with profound implications for the reproductive and metabolic health of women. The utilization of anthropometric measures in the diagnosis and management of PCOS has gained increasing attention due to their practicality and predictive capacity for associated conditions such as obesity and insulin resistance. This review rigorously explores the application of various anthropometric indices, including body mass index, waist-to-hip ratio, and advanced metrics such as the body shape index and body roundness index, wrist circumference, neck circumference. These indices offer critical insights into body fat distribution and its association with the metabolic and hormonal perturbations characteristic of PCOS. The review underscores the necessity of addressing obesity, a prevalent comorbidity in PCOS, through lifestyle modifications and personalized therapeutic approaches. By incorporating anthropometric evaluations into routine clinical practice, healthcare professionals can enhance diagnostic precision, optimize treatment strategies, and ultimately improve patient outcomes. This integrative approach not only facilitates the management of the metabolic challenges inherent in PCOS but also contributes to the development of more individualized therapeutic interventions, thereby enhancing the overall quality of life for women affected by PCOS.

The association between parity and type 2 diabetes mellitus: a cross-sectional, community-based study

BACKGROUND

Limited published data exist on the association between parity (number of deliveries) and diabetes mellitus (DM). This study was conducted to evaluate the association between parity and type 2 DM (T2DM) among Sudanese women.

METHOD

A multistage sampling survey was conducted in four villages in the River Nile State, Sudan, between July and September 2022. The World Health Organization's three-level stepwise questionnaire was adopted to collect women's sociodemographic characteristics (age, sex, height, weight, marital status, parity, education level, occupation, detailed obstetric history, and family history of T2DM). Multivariate analyses were performed.

RESULTS

A total of 397 women were recruited. Their median (interquartile range) age was 45.0 (33.0‒55.7) years. A total of 154 women (38.8%) were nulliparous, whereas 93 (23.4%), 70 (17.6%), and 80 (20.2%) had para 1‒3, 4 or 5, and more than 5, respectively. A total of 112 (28.2%) women had T2DM. In multivariate analysis, older age (adjusted odds ratio, AOR, 1.04, 95%, confidence interval, CI, 1.02‒1.06), high parity (AOR, 1.1, 95% C, 1.01‒1.20), and a family history of DM (AOR, 3.26, 95% CI, 1.98‒5.38) were associated with T2DM. Compared with the nulliparity, para 1‒3 (AOR, 2.33; 95% CI, 1.17‒4.61), para 4 or 5 (AOR, 2.12; 95% CI, 1.04‒4.30), and para > 5 (AOR, 2.16; 95% CI, 1.09‒4.27) were at higher risk of T2DM. In women aged < 50 years, high parity (AOR, 1.22; 95% CI, 1.06‒1.44) was associated with T2DM. Compared with the nulliparous women, para 4 or 5 (AOR, 3.47; 95% CI, 1.16‒10.34) and para > 5 (AOR, 4.63; 95% CI, 1.54‒13.87) were associated with T2DM, whereas para 1‒3 was not associated with T2DM. In the women aged ≥ 50 years, parity and parity groups were not associated with T2DM.

CONCLUSION

There is a high prevalence of T2DM among Sudanese women. Parity and high parity are significant predictors of T2DM among these women in this part of Sudan.

Association of triglyceride glucose index with cardiovascular events: insights from the Isfahan Cohort Study (ICS)

BACKGROUND

There is limited evidence regarding the evaluation of the association between the triglyceride glucose (TyG) index, an indicator of insulin resistance, and the incident risk of cardiovascular disease (CVD). Therefore, we aimed to examine the relationship between the TyG index and CVD incidence in a cohort of Iranian adults.

METHODS

This study was performed in the framework of the Isfahan Cohort Study (ICS). The study population included 5,432 individuals aged ≥ 35 years. CVD events, including acute myocardial infarction (MI), stroke, and unstable angina (UA), were diagnosed by physicians. The TyG index was calculated as Ln [fasting triglycerides (mg/dL) × fasting plasma glucose (mg/dL)/2]. The relationship between the TyG index and CVD events was investigated using Cox regression models. Receiver operating characteristics (ROC) curve analysis was used to determine the best cut-off for the TyG index for predicting CVD outcomes.

RESULTS

During a median follow-up period of 11.2 years, a total number of 819 CVD, 164 MI, 172 stroke, and 384 UA were recorded. Following adjustment for multiple confounders, elevated TyG levels were associated with a higher risk of CVD (HR = 1.48; 95% CI 1.22-1.79; p < 0.001), MI (HR = 2.24; 95% CI 1.42-3.52; p < 0.001), stroke (HR = 1.45; 95% CI 0.96-2.19; p = 0.042), but not UA (HR = 1.28; 95% CI 0.96-1.69). The optimal TyG index cut-off was 8.91 for predicting CVD (sensitivity 58%; specificity 58%), 9.04 for predicting MI (sensitivity 57%; specificity 65%), 8.92 for predicting stroke (sensitivity 57%; specificity 57%), and 8.98 for predicting UA (sensitivity 53%; specificity 61%).

CONCLUSION

We found a robust, direct association between the TyG index and the incidence of CVD events. This emphasizes the significance of observing the TyG index as an indicator of the occurrence of CVD events.

Three-year change in glycemic state and the future risk of incident hypertension among Iranian adults: Tehran Lipid and Glucose Study

The impact of 3-year change in glycemic state on the risk of hypertension among Tehranian adults aged ≥20 years was assessed. The study population included 1679 men and 2348 women who were non-diabetic normotensive at enrollment. The following categories were defined both at baseline visit and three years later (second visit): normoglycemia [normal fasting glucose (NFG) and normal glucose tolerance (NGT)] and prediabetes [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT)]. Changes in the categories, i.e., regression to normoglycemia, remaining in previous status, and progression to diabetes were assessed. Changes in fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG) categories were also considered separately. We used the Cox models adjusted for traditional hypertension risk factors to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). During a median follow-up of 9.4 years, 485 men and 589 women developed hypertension. Among men, considering both FPG and 2hPG, compared to individuals remaining normoglycemic, changing from prediabetes to normoglycemia had a HR of 1.30 (95% CI: 0.98-1.71; P-value: 0.064). Defining changes by 2hPG showed that compared to remaining NGT, incident IGT (progression from NGT to IGT) had a significant association with increased risk of hypertension development by a HR of 1.61 (1.13-2.30). Among women, on the other hand, change in glycemic state generally didn't show a significant association with incident hypertension. To sum up, change in glycemic state hadn't a significant association with hypertension development among women; however, compared to remaining NGT, men with incident IGT had a significant higher risk.

Islet function changes of post-glucose-challenge relate closely to 15 years mortality of elderly men with a history of hyperglycemia

Aims

We aimed to investigate the relationship between islet function changes during a glucose challenge and 15-year mortality in elderly men.

Methods

Elderly men who did the oral glucose tolerance test in 2005 owing to an abnormal glucose history without diabetes were included. Changes in insulin resistance and secretion were evaluated using the homeostasis model assessment (HOMA) of fast, post-load, and ratios. Comparisons between the dead and the survival groups were analyzed using the Student's t-test (continuous variables) or χ2 test (Categorical variables). Single-factor logistic regression was used to identify the possible affecting factors. Multifactorial logistic regression was used to identify the independent risk factors in total population and in the subgroups. ROC curve was used to assess the predictive ability of risk factor and to determine the cut-off value.

Results

Of the 220 elderly men, 67 died according to 15-year retrospection. Age (OR = 1.243, P = 0.000), diastolic pressure (OR = 0.958, P = 0.027), and HOMA-IR (2 h/0 h) (OR = 1.040, P = 0.010) were independent risk factors for 15-year mortality. Subgroup analysis showed that HOMA-IR (2 h/0 h) was an obvious risk factor, especially for normal glucose tolerance (OR = 1.060, P = 0.030), age 60-70 years (OR = 1.068, P = 0.005), and hypertension (OR = 1.048, P = 0.013); HOMA-β (2 h/0 h) showed some protective effects in the impaired glucose regulation subgroup (OR = 0.779, P = 0.057). HOMA-IR (2 h/0 h) cut-off value was 15.

Conclusions

HOMA-IR (2 h/0 h) higher than 15 was an independent risk factor for 15-year mortality in elderly men with hyperglycemia history.

Association of triglycerides to high-density lipoprotein cholesterol ratio to identify future prediabetes and type 2 diabetes mellitus: over one-decade follow-up in the Iranian population

BACKGROUND

To determine the association between triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) for identifying subjects at risk of incident prediabetes and type 2 diabetes mellitus (T2DM).

METHODS

In 5064 subjects (men = 2247) aged ≥ 20 years, using Cox proportional hazards regression analyses, the associations of TG/HDL-C with incident prediabetes and T2DM were examined among normoglycemic men and women. Furthermore, the association of this lipid ratio with incident T2DM was also assessed among prediabetic subjects (n = 1414). The multivariable analyses were adjusted for age, body mass index, waist-to-height ratio, wrist circumference, systolic blood pressure, family history of T2DM, education level, history of cardiovascular diseases, and fasting plasma glucose (FPG).

RESULTS

During a median follow-up of 11.2 years, 2140 new cases of prediabetes (men = 1070) and 360 incident T2DM (men = 152) were identified among normoglycemic individuals. In the prediabetic population, 574 new cases of T2DM (men = 252) were developed. Among the whole population, compared to the first quartile (reference), higher quartiles of TG/HDL-C were significantly associated with higher risks of incident prediabetes and T2DM among normoglycemic individuals and incident T2DM in the prediabetic population (all P for trend < 0.001). The corresponding hazard ratios (HRs) and 95% confidence intervals (CIs) for the fourth quartiles were 1.37(1.20-1.58), 1.92(1.34-2.75), and 1.57(1.22-2.01), respectively. The sex-stratified analyses demonstrated similar significant associations in both sexes; however, TG/HDL-C lost its association with incident T2DM among prediabetic men. Among the normoglycemic population, 1 unit increase in TG/HDL-C was significantly associated with incident prediabetes and T2DM [1.02(1.00-1.03) and 1.06(1.03-1.08), respectively]. The corresponding value for incident T2DM in prediabetic individuals was 1.01(1.00-1.03). In a subgroup population having insulin data (n = 2897), the associations between TG/HDL-C and incident prediabetes and T2DM among normoglycemic individuals generally persisted even after replacing FPG with an index of insulin resistance (IR), i.e., homeostasis model assessment of IR (HOMA-IR) in the adjusted model.

CONCLUSIONS

In conclusion, in the normoglycemic population, the increasing value of TG/HDL-C was unfavorably associated with incident prediabetes and T2DM, especially among women. Similarly, TG/HDL-C was associated with incident T2DM in prediabetic individuals. Generally, we found that the correlation between TG/HDL-C and different states of dysglycemia is independent of HOMA-IR.

Markers of insulin resistance in Polycystic ovary syndrome women: An update

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders, affecting 5%-10% of women of reproductive age. The importance of this syndrome lies in the magnitude of associated comorbidities: infertility, metabolic dysfunction, cardiovascular disease (CVD), plus psychological and oncological complications. Insulin resistance (IR) is a prominent feature of PCOS with a prevalence of 35%-80%. Without adequate management, IR with compensatory hyperinsulinemia contributes directly to reproductive dysfunction in women with PCOS. Furthermore, epidemiological data shows compelling evidence that PCOS is associated with an increased risk of impaired glucose tolerance, gestational diabetes mellitus and type 2 diabetes. In addition, metabolic dysfunction leads to a risk for CVD that increases with aging in women with PCOS. Indeed, the severity of IR in women with PCOS is associated with the amount of abdominal obesity, even in lean women with PCOS. Given these drastic implications, it is important to diagnose and treat insulin resistance as early as possible. Many markers have been proposed. However, quantitative assessment of IR in clinical practice remains a major challenge. The gold standard method for assessing insulin sensitivity is the hyperinsulinemic euglycemic glucose clamp. However, it is not used routinely because of the complexity of its procedure. Consequently, there has been an urgent need for surrogate markers of IR that are more applicable in large population-based epidemiological investigations. Despite this, many of them are either difficult to apply in routine clinical practice or useless for women with PCOS. Considering this difficulty, there is still a need for an accurate marker for easy, early detection and assessment of IR in women with PCOS. This review highlights markers of IR already used in women with PCOS, including new markers recently reported in literature, and it establishes a new classification for these markers.

The association of parity/live birth number with incident type 2 diabetes among women: over 15 years of follow-up in The Tehran Lipid and Glucose Study

Background

Childbearing may increase the future risk of developing type 2 diabetes mellitus (T2DM) in mothers. However, the issue is not clear completely and not investigated in the Middle East, a region with a high burden of T2DM. In the current study, we examined the association of parity/live birth number with incident T2DM among Iranian women.

Methods

The study population included 2552 women aged 30–65 years recruited in 1999–2001 and were followed for incident T2DM by 3-year intervals. Multivariable Cox proportional hazard models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of the parity/live birth number for incident T2DM. Parity number was defined as the number of live childbirth (number of live birth) plus the number of stillbirth (defined as birth of an infant that died after the 20th week of pregnancy in the uterus).

Results

During a median follow-up of 15.4 years, 557 incident T2DM cases have occurred. After adjustment for potential T2DM risk factors and reproductive factors, each additional parity caused a 9% higher risk for incident T2DM. Moreover, compared to women with one parity, those with 3 and ≥ 4 parity had HRs of 1.73 [95% CI: 1.06–2.83] and 2.23 [1.36–3.65], respectively. After further adjustment for body mass index (BMI) and waist circumference, although the HRs were attenuated prominently, parity ≥ 4 was associated with significantly higher risk (HR: 1.72 [1.05–2.83]); even after further adjustment for triglycerides (TG)/ high-density lipoprotein cholesterol (HDL-C), the risk remained marginally significant (HR: 1.64 [1.00–2.70; P value: 0.051]). For the number of live birth, the results were also similar. Moreover, in a sensitivity analysis, when we considered BMI change during follow-up as another covariate, generally, the effect sizes did not change; the trend of HRs across categories of parity number remained marginally significant (P value: 0.064).

Conclusions

During a long-term follow-up, after adjustment for potential T2DM risk factors, reproductive factors, obesity indices, and TG/HDL-C (insulin resistance surrogate), we demonstrated that higher parity/live birth numbers could be associated with increased risk of T2DM development among Iranian women. Moreover, even after further adjustment for BMI change, the suggestive higher risk was still found.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-021-01519-7.

The impact of triglyceride-glucose index on incident cardiovascular events during 16 years of follow-up: Tehran Lipid and Glucose Study

BACKGROUND

To investigate whether the Triglyceride-Glucose index (TyG-index) is associated with increased risk of cardiovascular diseases (CVD)/coronary heart disease (CHD).

METHODS

A total of 7521 Iranians aged ≥ 30 years (male = 3367) were included in the study. Multivariate Cox regression analyses (adjusted for age, gender, waist circumference, body mass index, educational level, smoking status, physical activity, family history of CVD, type 2 diabetes, hypertension, low and high density lipoprotein cholesterol, and lipid lowering drugs) were used to assess the risk of incident CVD/CHD across quintiles and for 1-standard deviation (SD) increase in the TyG-index. The cut off point for TyG-index was assessed by the minimum value of [Formula: see text]. We also examined the added value of the TyG-index in addition to the Framingham risk score when predicting CVD.

RESULTS

During follow-up, 1084 cases of CVD (male = 634) were recorded. We found a significant trend of TyG-index for incident CVD/CHD in multivariate analysis (both Ps for tend ≤ 0.002). Moreover, a 1-SD increase in TyG-index was associated with significant risk of CVD/CHD in multivariate analysis [1.16 (1.07-1.25) and 1.19 (1.10-1.29), respectively]. The cut-off value of TyG-index for incident CVD was 9.03 (59.2% sensitivity and 63.2% specificity); the corresponding value of TyG-index for incident CHD was 9.03 (60.0% sensitivity and 62.8% specificity), respectively. Although no interaction was found between gender and TyG-index for CVD/CHD in multivariate analysis (both Ps for interaction > 0.085), the significant trend of TyG-index was observed only among females for incident CVD (P = 0.035). A significant interaction was found between age groups (i.e. ≥ 60 vs < 60 years) and TyG-index for CVD outcomes in the multivariate model (P-value for interaction = 0.046). Accordingly, a significant association between the TyG-index and outcomes was found only among the younger age group. Among the population aged < 60 the addition of TyG-index to the Framingham risk score (FRS) did not show improvement in the predictive ability of the FRS, using integrated discrimination improvement.

CONCLUSION

The TyG-index is significantly associated with increased risk of CVD/CHD incidence; this issue was more prominent among the younger population. However, adding TyG-index to FRS does not provide better risk prediction for CVD.

Determinants of glycemic control: Phase 2 analysis from nationwide diabetes report of National Program for Prevention and Control of Diabetes (NPPCD-2018)

BACKGROUND

Diabetes is one of the leading causes of morbidity and mortality worldwide, especially among middle and low income nations. Many diabetic complications and comorbidities are attributable to poor glycemic control. The aim of this study was to update and extend the national diabetes reports on the status of comorbidities, diabetes care and complications in Iran. Moreover, we investigated the risk factors of poor glycemic control in the Iranian population.

METHODS

National database of 99,651 patients with diabetes who attended university-affiliated clinics between April 1, 2017 and February 30, 2018 was used to carry out a cross-sectional study. Stepwise backward selection logistic regression model was used to examine the associated factors of glycemic control.

RESULTS

In this study 73.0% and 56.5% of the enrolled population with diabetes, had hypertension and hyperlipidemia, respectively. The prevalence of patients who received education for nutrition therapy or diabetes self-management was 16.3% and 23.3% respectively. Poor glycemic control was associated with male gender (OR=1.06, p=0.001), obesity (OR=1.03, p=0.05), duration of diabetes (OR=1.018, p<0.001), smoking (OR=1.08, p=0.041), hypertension (OR=1.53, p<0.001), hyperlipidemia (OR=1.15, p<0.001), insulin therapy (OR=1.26, p<0.001) and combination of insulin and oral anti-diabetic agents compared to oral anti-diabetic agents alone (OR=2.36, p<0.001).

CONCLUSION

We demonstrated that the prevalence of diabetes comorbidities is high in Iranian population and that a great proportion of Iranian patients with diabetes had not reached the goal of glycemic control. Our findings provide a starting point from which to investigate the obstacles that prevent patients with diabetes from reaching metabolic targets.

Sex-Specific Incidence Rates and Risk Factors for Hypertension During 13 Years of Follow-up: The Tehran Lipid and Glucose Study

Background:

Hypertension, with a prevalence of 25.6% is a serious public health concern in Iran.

Objective:

To investigate the population-based incidence of hypertension and its potential risk factors in Tehranian adults during a median follow-up of 13.1 years.

Methods:

A total of 6,533 non-hypertensive participants (women = 3,639), aged ≥20 years participated in the study. Crude and age-standardized incidence rates per 1000 person-years were calculated for each sex, separately. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI) for all potential risk factors.

Results:

The crude and age-standardized incidence rates (95% CI) of hypertension per 1000 person-years were 29.7 (27.8–31.6) and 34.9 (32.5–37.4) among men and 25.8 (24.3–27.3) and 38.7 (35.5–42.0) among women, respectively. The incidence rate of hypertension in younger age groups was higher among men. However, after the 4^th decade, the incidence rate was higher among women. Significant interactions of sex with age groups, body mass index categories, marital status, hypertriglyceridemia and glycemic categories were found in multivariable analyses (all p-values < 0.05). In the multivariable model, the risk in both sexes was found to be significantly associated with older age, obesity, and normal or high normal blood pressure (BP). Moreover, factors such as being overweight [HR: 1.20 (1.00–1.44)], former smoking [2.15 (1.52–3.04)], hypertriglyceridemia [1.23 (1.06–1.43)] and pre-diabetes status [1.19 (1.02–1.39)] were significant predictors of incident hypertension among women. Central obesity was found to be a significant predictor among men [1.26 (1.03–1.54)]. The optimism-corrected Harrell’s C index (95% CI) in the categorical adjusted model was 0.75 (0.74–0.79) among men and 0.75 (0.74–0.76) among women.

Conclusion:

In the Tehranian population, nearly 2.7% of total participants (3% of men and 2.6% of women) develop hypertension each year. Obesity and high BP levels are the main modifiable risk factors in both sexes. Hypertriglyceridemia, prediabetes and former smoking are risk factors for hypertension among women.

Wrist circumference: A new marker for insulin resistance in African women with polycystic ovary syndrome

BACKGROUND

Insulin resistance (IR) is the main complication found in 35%-80% of women with polycystic ovary syndrome (PCOS). However, there is no definite consensus regarding which marker to use for its assessment in PCOS women. Research has shown that hyperinsulinemia is correlated with increased bone mass. Given that most women with PCOS are insulin resistant, which is independent from body fat and characterized by hyperinsulinemia, it could be hypothesized that there would be an increased bone mass in the patient as a result. Subsequently, increased bone mass could be measured using the wrist circumference method.

AIM

To assess the wrist circumference as an easy-to-detect marker of IR in Congolese women with PCOS.

METHODS

Seventy-two Congolese women with PCOS and seventy-one controls from the same ethnic group, were enrolled in the study (mean age 24.33 ± 5.36 years). Fasting biochemical parameters, and the Homeostasis Model Assessment of insulin resistance (HOMA-IR) and body composition were evaluated. The non-dominant wrist circumference was measured manually, as was the waist circumference (WC), hip circumference, height and weight. Calculated measures included evaluation of body mass index (BMI), Waist-to-Height (WHtR) and Waist-to-hip ratio (WHR). In addition, body composition was assessed by Bioelectrical Impedance Analysis using a body fat analyzer.

RESULTS

The non-dominant wrist circumference was more closely correlated with HOMA-IR (r = 0.346; P = 0.003) and was the best anthropometrical marker correlated with IR (P = 0.011 ) compared with other anthropometrical markers in women with PCOS: Dominant Wrist Circumference (r = 0.315; P = 0.007), Waist Circumference (WC) (r = 0.259; P = 0.028), BMI (r = 0.285; P = 0.016), WHR (r = 0.216; P = 0,068) and WHtR (r = 0.263; P = 0.027). The diagnostic accuracy of the non-dominant wrist circumference for the presence or absence of IR using Receiver-operating characteristic (ROC) curve analysis showed that the area under the ROC curve was 0.72. A cutoff value for the non-dominant wrist circumference of 16.3 cm was found to be the best predictor of IR in Congolese women with PCOS.

CONCLUSION

Non-dominant wrist circumference is, to date, the best anthropometrical marker of IR in Sub-Saharan African women with PCOS. It could be suggested as an easy-to-detect marker for assessing IR.

Association of wrist circumference with cardio-metabolic risk factors: a systematic review and meta-analysis

BACKGROUND AND AIMS

The association of Wrist Circumference (WrC) with cardio-metabolic risk factors is still contradictory. We aimed to systematically review the association of WrC with cardio-metabolic diseases among the general populations.

METHODS

We systematically searched electronic databases such as PubMed/Medline, Web of Sciences, and Scopus without language restriction until March 2017. Observational studies that examined the association of WrC with any cardio-metabolic risk factors were included. Pooled association of WrC with metabolic syndrome (MetS) was estimated using a random-effect model, and heterogeneity among studies was assessed by I² index and Q test.

RESULTS

A total of 14 papers including cohort study (n = 9), cross-sectional study (n = 4), and case-control study (n = 1) met the criteria and included. The eligible papers have been examined the association of WrC with any cardiovascular disorders (n = 8), metabolic syndrome (n = 4), insulin resistance (IR) (n = 5), diabetes mellitus (n = 2), impaired glucose tolerance (n = 1), cardio-metabolic risk factors (n = 2) and obesity/overweight (n = 1). In the whole population (both adults and pediatric population), high WrC increased the risk of MetS by 33% (Pooled OR = 1.33; 95% CI 1.20, 1.48; I² = 60.2%, p = 0.04), while the pooled OR in adult populations was 1.27 (95% CI 1.15-1.41; I²: 32.8%, p = 0.21). Qualitative synthesis showed that associations of WrC with other cardio-metabolic risk factors are conflicting.

CONCLUSION

High WrC increased the risk of MetS and other cardio-metabolic risk factors. However, due to limited studies, particularly in children, results should be declared with great caution. Further cohort studies are needed to clarify whether WrC is a suitable anthropometric index to predict cardio-metabolic disorders in adult and children populations in different societies.

LEVEL OF EVIDENCE

Level 1, systematic review and meta-analysis.

Blood Pressure and Hypertension: Findings from 20 Years of the Tehran Lipid and Glucose Study (TLGS)

CONTEXT

Hypertension (HTN) is a well-known modifiable risk factor for cardiovascular disease (CVD), chronic kidney disease and mortality. Positive effects of blood pressure (BP) lowering for prevention of CVD and death have been documented in several meta-analyses of randomized controlled trials.

EVIDENCE ACQUISITION

This review focuses on the key findings derived from the Tehran lipid and glucose study (TLGS) papers on different aspects of BP and HTN.

RESULTS

A prevalence of 23% for HTN has been reported in the TLGS population, aged ≥ 20 years. Over a decade long follow-up, the crude incidence rate (95% CI) of new-onset HTN defined as systolic BP (SBP) ≥ 140 mmHg and/or diastolic BP (DBP) ≥ 90 mmHg, and not using antihypertensive medication was 33.63 (32.0 - 35.3) per 1000 person-years. Age, baseline SBP and body mass index were significant risk factors for development of isolated systolic HTN; regarding isolated diastolic HTN, baseline DBP and waist circumference were recognized as important risk factors whereas age, female gender and marriage were shown to be protective factors. SBP decreased significantly in both diabetic and non-diabetic participants; DBP showed a non-significant decrease in diabetic men and a statistically significant decrease in non-diabetic men. Among women, both those with and without diabetes (DM) generally experienced statistically significant decreases in DBP. Cox proportional hazard models showed that neither SBP nor DBP were associated with incident DM in the total population and in either gender, separately. All BP components were associated with CVD and all-cause mortality in the middle-aged population. Contribution of HTN to cerebrovascular events was also documented in the TLGS participants, aged ≥ 50 years.

CONCLUSIONS

Several important findings regarding BP/HTN have been derived from the TLGS. According to data regarding the prevalence and incidence of preHTN and HTN and their contribution to cardiovascular morbidity and mortality in the TLGS population as a representative sample of Tehranian population, it is recommended that interventions be prioritized for lifestyle modifications for the prevention and appropriate management of preHTN/HTN.

Serum Lipids During 20 Years in the Tehran Lipid and Glucose Study: Prevalence, Trends and Impact on Non-Communicable Diseases

CONTEXT

Dyslipidemia, including elevated serum total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and triglycerides (TG), and low high density lipoprotein cholesterol (HDL-C) is a major modifiable risk factor for non-communicable diseases (NCDs). This review summarizes many of the key findings on lipid measures in the Tehran lipid and glucose study (TLGS), a large scale community-based study with an approximately two decade follow-up.

EVIDENCE ACQUISITION

A systematic literature search was conducted using PubMed, Scopus, Web of Science databases, and the library of the Research Institute for Endocrine Sciences, using the following keywords: Lipid measures, lipid ratios, lipid profile, dyslipidemia, and "Tehran lipid and glucose study". Articles were categorized based on fields of prevalence, trends, and impact of lipid profile on incident NCDs and mortality.

RESULTS

Between 1999 - 2001, the prevalence of high risk lipids ranged from 14% (low HDL-C) to 17% (high LDL-C) among adolescents, although among adults the lowest and highest prevalence were observed for low HDL-C (19%) and high TG (28%). Despite favorable trends for lipid parameters among adolescents, adults, and the elderly population, a considerable number of diabetic individuals, failed to achieve the optimum level of serum lipids. During follow-up, consumption of lipid-lowering drugs increased from 1.5 to 9.0% and 3.7 to 11.4% among adult men and women, respectively. The association between different lipid parameters and related ratios for incident type 2 diabetes (T2D), hypertension, metabolic syndrome and cardiovascular diseases differed between genders. Interestingly, each 1-unit increase in TC/HDL-C increased risk of hypertension among women (odds ratio (OR): 1.19, 95% confidence interval (CI): 1.00 - 1.27) and T2D among men (OR: 1.27, 95% CI: 1.06 - 1.51). Moreover, TC, LDL-C, non-HDL-C, Ln-TG, TC/HDL-C, and Ln-TG/HDL were inversely associated with non-cardiovascular mortality.

CONCLUSIONS

Despite high prevalence of high risk lipid profiles among the TLGS population at baseline, favorable trends were observed in levels of all lipid components, which might be attributable to increased consumption of lipid-lowering medications and improvement in the general knowledge of Iranians regarding limited consumption of hydrogenated oil. Considering the impact of lipid profiles on incident NCDs, more attention should be paid to at-risk groups for screening and treatment purposes.

Tobacco Smoking: Findings from 20 Years of the Tehran Lipid and Glucose Study

CONTEXT

Smoking is a global public health priority and accurate data of the local population is essential to improve the health policies against its use. Hence, this study aimed to summarize the important findings available on the prevalence of smoking and its association with non-communicable diseases, documented by one of the largest prospective community-based studies of Iran.

EVIDENCE ACQUISITION

All articles derived from the Tehran Lipid and Glucose Study (TLGS) in the last two decades, from the earliest publications until 30 January 2018 were reviewed for their findings on tobacco smoking.

RESULTS

The prevalence of smoking in non-diabetic adults ≥ 20 years increased between baseline (phase I, 1999 - 2001) and follow-up (phase V, 2008 - 2011) from 25.5% to 35.4% among men and from 3.4% to 6.8% among women. In TLGS adolescents (10 - 18 years) water pipe use increased between 2003 and 2005 from 35.5% to 40.9% among boys and from 19.7% to 26.1% among girls. Regarding health hazards, smoking in men was associated with increased risk of combined impaired fasting glucose/impaired glucose tolerance [hazard ratio (HR) 1.69; confidence interval (CI) 95% 1.15 - 2.48] and hypertension (HR 1.26; CI 95% 0.98 - 1.63). Moreover, men, even smoking less than 10 cigarettes per day, were at increased risk for cardiovascular diseases by HR 2.12 (CI 95% 1.14 - 3.95). For women, the risk of chronic kidney disease dramatically increased 5.74-fold (CI 95% 2.71 - 12.15) among smokers. In the whole population, smoking contributed to 7.7% of all-cause mortality with HR 1.75 (CI 95% 1.38 - 2.22). Other health aspects of tobacco smoke, including its impact on metabolic status, thyroid function, female reproductive system and life style have also been reviewed.

CONCLUSION

Considering hazards of smoking, there is the urgency for more effective preventive measures in Iran; emphasizing the need for further local studies on the hazards of smoking with special attention to women and adolescents and the independent hazards of water pipe use.

Low total and free triiodothyronine levels are associated with insulin resistance in non-diabetic individuals

This study examined associations of thyroid hormone levels and insulin resistance (IR) in non-diabetic individuals. Using a cross-sectional design, 2007-2008 data from the National Health and Nutrition Examination Survey (NHANES) were analyzed. NHANES participants ≥20 years of age with complete data of interest were included. The homeostatic model assessment (HOMA) was used to quantify IR, and treated as a continuous variable. Self-reported diabetes or a fasting glucose ≥7 mmol/L were used as criteria to exclude diabetic subjects. Race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, hemoglobin A1C (HbA1C), high-density lipoprotein, triglyceride, vitamin D and C-reactive protein were covariates significantly associated with HOMA-IR. A total of 1,560 non-diabetic subjects were included in the analysis. When adjusted for all factors significant in the univariate analysis (race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, HbA1C, high-density lipoprotein, triglyceride, vitamin D, and CRP) low total triiodothyronine (TT3) and low free T3 (FT3) were significantly associated with decreased HOMA-IR (adjusted coefficient = -0.486, 95% confidence interval [CI]: -0.936, -0.036; adjusted coefficient = -1.151, 95% CI: -1.952, -0.350, respectively). Insulin resistance is associated with low thyroid hormone levels in non-diabetic individuals.