J‐shaped relationship between waist circumference and subsequent risk for Type 2 diabetes: an 8‐year follow‐up of relatively lean Japanese individuals

Aims This study investigated the relationship between waist circumference and the subsequent incidence of Type 2 diabetes and the association with insulin resistance and pancreatic B‐cell function in relatively lean Japanese individuals. Methods The study participants were 3992 employees (2533 men and 1459 women, aged 35–55 years) of a metal‐products factory in Japan. The incidence of diabetes was determined in annual medical examinations during an 8‐year follow‐up. We calculated age‐ and sex‐adjusted hazard ratios (HRs) according to the sex‐specific quintile of waist circumference at baseline. Differences in baseline insulin resistance [homeostatis model assessment (HOMA)‐IR] and pancreatic B‐cell function (HOMA‐B) were compared between participants who developed diabetes and those who did not. Results During the follow‐up, 218 participants developed diabetes. Age‐ and sex‐adjusted HRs across the quintiles of waist circumference were 1.78, 1.00 (reference), 1.59, 3.11 and 3.30, respectively (P for trend, < 0.0001). The HR for the lowest quintile was significantly higher than that for the second quintile. Among participants with waist circumference of the lowest quintile, HOMA‐B was lower in those who developed diabetes than in those who did not [33.1 (24.1–45.0) vs. 54.3 (37.9–74.6) median (interquartile range), P < 0.0001], but HOMA‐IR did not differ between these groups. Conclusions There was a J‐shaped relationship between waist circumference and subsequent risk for Type 2 diabetes in relatively lean Japanese individuals; lower pancreatic B‐cell function may also increase the risk of diabetes in very lean Japanese people.     

Hip circumference,height and risk of type 2 diabetes: systematic review and meta‐analysis

Although several epidemiological studies have investigated the relationship between type 2 diabetes mellitus (T2DM) and hip circumference or height, the results are inconsistent. The present systematic review and meta‐analysis of published observational studies was conducted to assess the effects of hip circumference and height on diabetes risk. Online databases were searched through January 2012, and the reference lists of pertinent articles reporting observational studies in humans were examined. Pooled relative risks (RR) and 95% confidence intervals (CI) were calculated with a random‐effects model. Eighteen studies (nine cross‐sectional and nine cohort) were included, with 250,497 participants and 7,765 cases of T2DM. Hip circumference was inversely associated with an increased risk of T2DM in men (summary RR [95% CI] 0.60 [0.45, 0.80]) and women (0.54 [0.42, 0.70]). These results were consistent between cross‐sectional and cohort studies. An inverse association between height and T2DM was observed in women only (summary RR [95% CI] 0.83 [0.73, 0.95]). Our meta‐analysis strongly supports an inverse relationship between hip circumference and risk of T2DM in men and women. The inverse association between height and risk was significant only in women.     

A systematic review of the impact of including both waist and hip circumference in risk models for cardiovascular diseases,diabetes and mortality

Both a larger waist and narrow hips are associated with heightened risk of diabetes, cardiovascular diseases and premature mortality. We review the risk of these outcomes for levels of waist and hip circumferences when terms for both anthropometric measures were included in regression models. MEDLINE and EMBASE were searched (last updated July 2012) for studies reporting the association with the outcomes mentioned earlier for both waist and hip circumferences (unadjusted and with both terms included in the model). Ten studies reported the association between hip circumference and death and/or disease outcomes both unadjusted and adjusted for waist circumference. Five studies reported the risk associated with waist circumference both unadjusted and adjusted for hip circumference. With the exception of one study of venous thromboembolism, the full strength of the association between either waist circumference or hip circumference with morbidity and/or mortality was only apparent when terms for both anthropometric measures were included in regression models. Without accounting for the protective effect of hip circumference, the effect of obesity on risk of death and disease may be seriously underestimated. Considered together (but not as a ratio measure), waist and hip circumference may improve risk prediction models for cardiovascular disease and other outcomes.     

Adiposity measures and pre‐diabetes or diabetes in adults with hypertension in Singapore polyclinics

Identification of hypertensive patients with pre‐diabetes or diabetes is important for timely prevention of complications including vascular disease. We aimed to compare the association and discrimination of central obesity measures (waist circumference [WC] and waist‐to‐height ratio [WHtR]) with generalized obesity measure (body mass index [BMI]) in relation to pre‐diabetes and diabetes among a group of Asian hypertensive patients for the first time. We used the baseline data of 925 subjects aged 40 years or older with uncontrolled hypertension recruited at eight primary care clinics in Singapore. Information on height, weight, WC, fasting blood glucose, and hemoglobin A1c (HbA1c) was collected. Pre‐diabetes or diabetes was defined as having reported physician‐diagnosed diabetes or taking anti‐diabetes medication, fasting blood glucose ≥ 5.6 mmol/dL or HbA1c ≥ 5.7%. Among 925 subjects, 495 (53.5%) had pre‐diabetes or diabetes. In logistic regression models, BMI was not associated with pre‐diabetes or diabetes after adjusting for WC or WHtR, while a positive association remained with both WC and WHtR after adjustment of BMI. Both WC and WHtR had significantly better discrimination than BMI (respective area under ROC curve: 0.63 for WC, 0.63 for WHtR, and 0.60 for BMI; P = 0.019), and adding WC or WHtR on top of BMI further correctly reclassified 42.7% and 38.7% hypertensive patients to the right risk group of pre‐diabetes or diabetes indicated by net reclassification improvement. However, WHtR was not superior to WC. In conclusion, our results suggested that central obesity has stronger association with and better discrimination for pre‐diabetes or diabetes than generalized obesity.     

Percentile distributions of waist circumference for 7–19‐year‐old Polish children and adolescents

The aim of the study was to develop waist circumference (WC) percentiles in Polish children and youth and to compare these with the results obtained in other countries. The study comprised a random group of 5663 Polish children aged 7–18 years. Smoothed WC percentile curves were computed using the LMS method. The curves displaying the values of the 50th (WC₅₀) and the 90th (WC₉₀) percentile were then compared with the results of similar studies carried out in children from the UK, Spain, Germany, Turkey, Cyprus, Canada and the USA. WC increased with age in both boys and girls and in all observed age periods the boys were seen to dominate. For 18‐year‐old Polish boys and girls the values of WC₉₀ were 86.5 and 78.2, respectively, and were lower than the current criteria developed by the International Diabetes Federation. Both WC₅₀ and WC₉₀ were higher in Polish boys and girls compared with their counterparts in the UK, Turkey and Canada and significantly lower than in children from the USA, Cyprus and Spain. The percentile curves for Polish children and youth, which were developed here for the first time, are base curves that can be applied in analysing trends as well as making comparisons with results of similar studies performed in other countries.     

Incidence of diabetic retinopathy in Bangladesh: A 15‐year follow‐up study*

Background: The aim of the present study was to estimate the incidence of diabetic retinopathy (DR) among type 2 diabetic (T2D) subjects in Bangladesh. Methods: A random sample of 977 patients with T2D was recruited retrospectively in 2008 from newly diagnosed T2D patients who had attended the Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic Disorder (BIRDEM) in 1993. Baseline information for the cohort was collected for 1993 from hospital records. The mean time until development of DR in newly diagnosed T2D patients was calculated using survival analysis. Cox’s proportional hazards model was used to assess factors affecting the time until development of DR. Results: The cumulative incidence of DR over the 15‐year period was 50.6% (95% confidence interval [CI] 47.5%–53.8%). The incidence density (per 100 person‐years) of DR was similar in the overall cohort (4.1; 95% CI 3.7–4.5) and in men (4.2; 95% CI 3.7–4.7) and women (4.1; 95% CI 3.6–4.6) separately. The mean time (in years) until development of DR in the cohort was 9.72 (95% CI 9.38–10.06), with similar times in men (9.8; 95% CI 9.3–10.3) and women (9.6; 95% CI 9.5–10.1) analyzed separately. Age, sex, hypertension, lipid profile, HbA1c, and serum creatinine were entered into the hazards model simultaneously. However, only age (hazard ratio [HR] 0.75; 95% CI 0.61–0.92) and HbA1c (HR 0.52; 95% CI 0.33–0.82) had a significant effect on the time until development of DR. Conclusions: Glucose deregulation is the most important factor in the development of DR.     

Beta cell stress in a 4‐year follow‐up of patients with type 2 diabetes: A longitudinal analysis of the BetaDecline Study

Background

Type 2 diabetes mellitus (T2DM) is associated with a progressive deterioration in beta cell function and loss of glycaemic control. Clinical predictors of beta cell failure are needed to guide appropriate therapy.

Methods

A prospective evaluation of a large set of potential predictors of beta cell stress, measured as change in the proinsulin/insulin (PI/I) ratio, was conducted in a cohort of 235 outpatients with T2DM on stable treatment with oral hypoglycaemic agents or diet followed up for ~4 years (median value 3.9 years; interquartile range 3.8‐4.1 years).

Results

Overall, metabolic control deteriorated over time, with a significant increase in glycated haemoglobin (HbA1c; P < .0001), proinsulin (P < .0001), and PI/I ratio (P = .001), without significant changes in the homeostatic model assessment of insulin resistance. Multivariate regression analysis showed that for each 1% (10.9 mmol/mol) increase from baseline in HbA1c, the risk of beta cell stress increased by 3.8 times; for each 1% (10.9 mmol/mol) incremental increase in HbA1c during the study, risk of beta cell stress increased by 2.25 times that at baseline. By contrast, baseline anthropometric and clinical variables, lipid profile, inflammatory markers (PCR, IL‐6), non‐esterified fatty acids, and current therapies did not independently influence PI/I ratio variation during follow‐up.

Conclusions

In this cohort of patients with T2DM, beta cell function progressively deteriorated despite current therapies. Among a large set of clinical and biochemical predictors, only baseline HbA1c levels and their deterioration overtime were associated with higher beta cell stress over time.