The increasing global prevalence of diabetes mellitus presents a significant challenge to healthcare systems today. Although diabetic retinopathy, nephropathy and neuropathy are well‐established complications of diabetes, there is a paucity of research examining the impact of dysglycaemia on the olfactory system. Olfaction is an important sense, playing a role in the safety, nutrition and quality of life of an individual, but its importance is often overlooked when compared with the other senses. As a result, olfactory dysfunction is often underdiagnosed. The present review article aims to present and discuss the available evidence on the relationship between diabetes and olfaction. It also explores the associations between olfactory dysfunction and diabetes complications that could explain the underlying pathogenesis. Finally, it summarizes the putative pathological mechanisms underlying olfactory dysfunction in diabetes that require further investigation.

The comorbidities related to obesity are already extensive, but as the prevalence of obesity increases globally, so do the number of its associated conditions. The relationship between hearing impairment and obesity is a relatively recent research interest, but is significant as both conditions have the ability to substantially reduce an individual’s quality of life both physically and psychologically. Obesity has a significant effect on vascular function, and this may have an impact on highly vascular organs such as the auditory system. This review aims to provide an overview of the existing literature surrounding the association between hearing loss and obesity, in order to emphasise these two highly prevalent conditions, and to identify areas of further investigation. Our literature search identified a total of 298 articles with 11 articles of relevance to the review. The existing literature in this area is sparse, with interest ranging from obesity and its links to age-related hearing impairment (ARHI) and sudden sensorineural hearing loss (SSNHL), to animal models and genetic syndromes that incorporate both disorders. A key hypothesis for the underlying mechanism for the relationship between obesity and hearing loss is that of vasoconstriction in the inner ear, whereby strain on the capillary walls due to excess adipose tissue causes damage to the delicate inner ear system. The identified articles in this review have not established a causal relationship between obesity and hearing impairment. Further research is required to examine the emerging association between obesity and hearing impairment, and identify its potential underlying mechanisms.

Aims To summarize the association between obstructive sleep apnoea and diabetic retinopathy and diabetic maculopathy, and to examine the effects of oxygen desaturation index, mean and minimum oxygen saturation and time spent with < 90% oxygen saturation on diabetic retinopathy and diabetic maculopathy.Methods A systematic search was performed for papers published from inception to January 2014 in MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews using indexed terms and free text. Additional searches were carried out for grey literature. Two authors conducted the study selection and quality assessment. Data extraction was performed by the main author and checked by the other authors.Results One cohort study and 15 cross-sectional studies were included for narrative synthesis and three for meta-analyses. There was no convincing evidence that obstructive sleep apnoea was associated with diabetic retinopathy, although some evidence suggested that obstructive sleep apnoea was associated with greater severity of diabetic retinopathy and advanced diabetic retinopathy in people with Type 2 diabetes. Only six studies examined the impact of obstructive sleep apnoea on diabetic maculopathy and our narrative review suggests there is an association in Type 2 diabetes. Oxygen desaturation index, mean oxygen saturation or time spent with < 90% oxygen saturation were not associated with diabetic retinopathy, and insufficient evidence was available to draw conclusions on their effects on diabetic maculopathy; however, there was evidence from both narrative synthesis and meta-analysis that minimum oxygen saturation had an impact on diabetic retinopathy (pooled odds ratio 0.91, 95% CI 0.87-0.95; I-2 = 0%).Conclusions There is a need for large cohort studies with long-term follow-up data to examine the long-term effects of obstructive sleep apnoea and other sleep variables on advanced retinal disease in diabetes.

Aims: an association between T2DM and cognitive impairment has been reported among Western populations, but data are limited in other settings. We investigated the cross-sectional association between fasting blood glucose (FBG) and cognition in an older Chinese population.Methods: the Guangzhou Biobank Cohort Study included 27,971 individuals (50-96 years, mean age 61.5 years, 72% female) with measures of cognitive function assessed using modified Delayed Word Recall Test (DWRT) and Mini-Mental State Examination (MMSE). Fasting glucose and lipids, and potential confounders were measured.Results: after adjustment for potential confounders, the risk for cognitive impairment as measured by DWRT, significantly increased [odds ratio (OR) = 1.18, 95% CI 1.00-1.40] but the association was of borderline significance when measured by MMSE (OR = 1.04, 95% CI 0.73-1.47) in those with diabetes relative to those without diabetes. Fasting blood glucose was significantly negatively associated with cognitive function as measured by DWRT but not MMSE, with an increase of 1 mmol/l of FBG associated with a decrease of 0.02 in DWRT (P < 0.05, 95% CI -0.03 to -0.002) and 0.03 in MMSE score (P = 0.114, 95% CI -0.06-0.01).Conclusions: an FBG level indicative of T2DM was associated with increased risk for cognitive impairment. The findings also demonstrate that glycaemia is continuously associated with cognitive impairment, suggesting that dysfunction is associated with increasing glucose levels even in the normoglycaemic range.

Background/objectives: Levels of pediatric obesity continue to rise. Previous evidence has linked short sleep duration and/or poor sleep quality to obesity development, although objective data are limited. As adolescents transition through puberty, circadian shifts occur, resulting in sleep loss. However, little is known whether chronotype is associated with body mass index (BMI) or dietary behaviors in adolescents. We hypothesized late chronotype would be positively associated with BMI and poorer dietary behaviors. Subjects/methods: A total of 511 UK young adolescents (11–13 years) from eight secondary schools across the Midlands region (UK) participated in the Midlands Adolescent Schools Sleep Education Study (MASSES), a cross-sectional study to assess potential relationships between chronotype and BMI z -score as well as dietary habits. Height (cm) and weight (kg) were objectively measured for BMI calculation and participants completed a questionnaire to assess dietary habits. A subsample of 236 adolescents wore wrist actigraphy for 7 days to estimate average sleep duration (weekday, weekend and combined) and sleep efficiency. Results: Definitely evening chronotype was positively associated with BMI z -score compared to definitely morning chronotypes β=0.51, P <0.01, after adjustment. Higher frequency of consuming unhealthy snacks, night-time caffeine consumption and inadequate daily intake of fruit/vegetables were also associated with later chronotype (all P ⩽0.01). Actigraphy estimated sleep duration was an independent predictor of BMI z -score β=−0.36, P <0.001. Sleep efficiency did not predict BMI z -score after adjustment, β=−0.03, P =0.07. Conclusions: Later chronotype young adolescents are at risk of increased BMI and poorer dietary behaviors. Although short sleep duration, but not sleep efficiency, was also an independent risk factor for increased BMI, different mechanisms may be driving the late chronotype and shorter sleep duration associations with BMI in this age group. Sleep hygiene education may help adolescents to better understand the impact of sleeping habits on physical health.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder whose prevalence is strongly linked to the current epidemic of obesity in many western countries. The prevalence of NAFLD is two to four times higher in populations with pre-existing metabolic comorbidities than in the general population. The diagnosis of primary NAFLD involves establishing the presence of hepatic steatosis or steatohepatitis by imaging or histology, along with establishing the non-alcoholic nature of the disease process and excluding competing aetiologies for hepatic steatosis. Among the indirect serum biomarkers, the NAFLD fibrosis score can help to identify patients with NAFLD and with higher likelihood of having fibrosis or cirrhosis. A liver biopsy should be considered in NAFLD patients at increased risk for steatohepatitis/advanced fibrosis and in cases where a liver biopsy is necessary to exclude co-existing chronic liver diseases and other aetiologies for hepatic steatosis. The treatment and management recommendations for obesity-associated NAFLD are aimed towards weight reduction. The currently available interventions employed to promote weight loss and improve the metabolic responses in NAFLD include lifestyle modification, pharmacotherapy and bariatric surgery.

Summary What is already known about this subject Technology use and ownership is highly prevalent in adolescents and has been previously linked to obesity, but bedtime use of contemporary, original and multiple device use is currently unexplored. Sleep duration is a potentially important contributor to obesity development, but other sleep parameters may be crucial and may contribute to a better understanding of obesity, although these are currently limited in adolescent samples. Adolescent obesity may have a negative impact on academic performance, but data are heterogeneous. Body mass index may also influence academic aspiration, but little is known about this potential relationship. What this study adds Frequent use of contemporary (video games) and long‐standing technologies (television) as well as multiple quantities of technology during the week at bedtime is positively associated with body mass index emphasizing the complex relationships between lifestyle choices during adolescence and obesity. We show that sleep duration and sleep onset latency are important aspects associated with elevated body mass index. Considering the physiological changes commonly associated with sleep alterations during adolescence, it is possible that incorporating sleep education into the curriculum and improving sleep hygiene may help to improve the current obesity epidemic, which impacts on many aspects of an individual's life. Increased body mass index is negatively associated with academic performance, but not aspiration, demonstrating the importance of tackling adolescent obesity for future health, well‐being and success. Background Contemporary technology and multiple device use may link to increased body mass index ( BMI ). The sleep–obesity relationship is inconsistent in adolescents. Sleep duration and quality may have crucial connections to obesity development, particularly in adolescents where sleep alterations are common. Elevated BMI in adolescents may influence academic performance and aspiration, but data are limited. Objectives The objectives of this study was to assess the linear associations between BMI z ‐score and (i) quantity/type of technology used; (ii) sleep quantity/quality and (iii) academic performance/aspiration. Methods Consenting adolescents ( n = 624; 64.9% girls, aged 11–18 years) were recruited. The S chools S leep H abits S urvey and T echnology U se Q uestionnaire were administered. Objective measures of height/weight were obtained. Results Quantity of technology was positively associated with BMI z ‐score β = 0.10, P < 0.01. Those who always engaged in video gaming had significantly higher BMI z ‐score vs. never‐users, β = 1.00, P < 0.001. Weekday sleep duration and sleep onset latency were related to BMI z ‐score, β = −0.24, P < 0.001 and β = 0.01, P < 0.001, respectively. An inverse linear association was observed between BMI z ‐score and academic performance, β = −0.68, P < 0.001. Conclusions If confirmed prospectively, reducing bedtime use of technology and improving sleep hygiene in adolescents could be an achievable intervention for attenuating obesity with potentially positive effects on academic performance.

Objective: To examine the independent associations between sleep duration, four technology types (computer use, mobile telephones, TV viewing and video gaming) and body mass index (BMI) z -score. We propose a theoretical path model showing direct effects of four technology types on BMI z -score and sleep duration as well as the indirect effects of each technology on BMI z -score while considering sleep duration as a mediator. Methods: Consenting adolescents ( n =632; 63.9% girls, aged 11–18 years) were recruited to the Midlands Adolescent Schools sleep Education Study. The School Sleep Habits Survey (SSHS) and Technology Use Questionnaire (TUQ) were administered. Objective measures of height (cm) and weight (kg) were obtained for BMI z -score calculation. Results: Weekday use of all technology types was significantly associated with reduced weekday sleep duration after adjustment (β (computer use)=−0.38, P <0.01; β (mobile telephone)=−0.27, P <0.01; β (TV viewing)=−0.35, P <0.01; and β (video gaming)=−0.39, P <0.01). Use of all technology types, with the exception of mobile telephones, was significantly associated with increased BMI z -score after adjustment (β (computer use)=0.26, P <0.01; β (TV viewing)=0.31, P <0.01; and β (video gaming)=0.40, P <0.01). Our path model shows that weekday sleep duration was significantly and negatively associated with BMI z -score (β=−0.40, P <0.01). Conclusion: Weekday sleep duration potentially mediates the effects of some technologies on BMI z -score. If confirmed, improving sleep through better management of technology use could be an achievable intervention for attenuating obesity.