Physical activity and the risk of progression of retinopathy or the development of proliferative retinopathy

Prognostic factors for the development and progression of proliferative diabetic retinopathy in people with diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is characterised by neurovascular degeneration as a result of chronic hyperglycaemia. Proliferative diabetic retinopathy (PDR) is the most serious complication of DR and can lead to total (central and peripheral) visual loss. PDR is characterised by the presence of abnormal new blood vessels, so-called "new vessels," at the optic disc (NVD) or elsewhere in the retina (NVE). PDR can progress to high-risk characteristics (HRC) PDR (HRC-PDR), which is defined by the presence of NVD more than one-fourth to one-third disc area in size plus vitreous haemorrhage or pre-retinal haemorrhage, or vitreous haemorrhage or pre-retinal haemorrhage obscuring more than one disc area. In severe cases, fibrovascular membranes grow over the retinal surface and tractional retinal detachment with sight loss can occur, despite treatment. Although most, if not all, individuals with diabetes will develop DR if they live long enough, only some progress to the sight-threatening PDR stage.  OBJECTIVES: To determine risk factors for the development of PDR and HRC-PDR in people with diabetes and DR.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 5), Ovid MEDLINE, and Ovid Embase. The date of the search was 27 May 2022. Additionally, the search was supplemented by screening reference lists of eligible articles. There were no restrictions to language or year of publication.  SELECTION CRITERIA: We included prospective or retrospective cohort studies and case-control longitudinal studies evaluating prognostic factors for the development and progression of PDR, in people who have not had previous treatment for DR. The target population consisted of adults (≥18 years of age) of any gender, sexual orientation, ethnicity, socioeconomic status, and geographical location, with non-proliferative diabetic retinopathy (NPDR) or PDR with less than HRC-PDR, diagnosed as per standard clinical practice. Two review authors independently screened titles and abstracts, and full-text articles, to determine eligibility; discrepancies were resolved through discussion. We considered prognostic factors measured at baseline and any other time points during the study and in any clinical setting. Outcomes were evaluated at three and eight years (± two years) or lifelong.  DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from included studies using a data extraction form that we developed and piloted prior to the data collection stage. We resolved any discrepancies through discussion. We used the Quality in Prognosis Studies (QUIPS) tool to assess risk of bias. We conducted meta-analyses in clinically relevant groups using a random-effects approach. We reported hazard ratios (HR), odds ratios (OR), and risk ratios (RR) separately for each available prognostic factor and outcome, stratified by different time points. Where possible, we meta-analysed adjusted prognostic factors. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.   MAIN RESULTS: We screened 6391 records. From these, we identified 59 studies (87 articles) as eligible for inclusion. Thirty-five were prospective cohort studies, 22 were retrospective studies, 18 of which were cohort and six were based on data from electronic registers, and two were retrospective case-control studies. Twenty-three studies evaluated participants with type 1 diabetes (T1D), 19 with type 2 diabetes (T2D), and 17 included mixed populations (T1D and T2D). Studies on T1D included between 39 and 3250 participants at baseline, followed up for one to 45 years. Studies on T2D included between 100 and 71,817 participants at baseline, followed up for one to 20 years. The studies on mixed populations of T1D and T2D ranged from 76 to 32,553 participants at baseline, followed up for four to 25 years.  We found evidence indicating that higher glycated haemoglobin (haemoglobin A1c (HbA1c)) levels (adjusted OR ranged from 1.11 (95% confidence interval (CI) 0.93 to 1.32) to 2.10 (95% CI 1.64 to 2.69) and more advanced stages of retinopathy (adjusted OR ranged from 1.38 (95% CI 1.29 to 1.48) to 12.40 (95% CI 5.31 to 28.98) are independent risk factors for the development of PDR in people with T1D and T2D. We rated the evidence for these factors as of moderate certainty because of moderate to high risk of bias in the studies.  There was also some evidence suggesting several markers for renal disease (for example, nephropathy (adjusted OR ranged from 1.58 (95% CI not reported) to 2.68 (2.09 to 3.42), and creatinine (adjusted meta-analysis HR 1.61 (95% CI 0.77 to 3.36)), and, in people with T1D, age at diagnosis of diabetes (< 12 years of age) (standardised regression estimate 1.62, 95% CI 1.06 to 2.48), increased triglyceride levels (adjusted RR 1.55, 95% CI 1.06 to 1.95), and larger retinal venular diameters (RR 4.28, 95% CI 1.50 to 12.19) may increase the risk of progression to PDR. The certainty of evidence for these factors, however, was low to very low, due to risk of bias in the included studies, inconsistency (lack of studies preventing the grading of consistency or variable outcomes), and imprecision (wide CIs). There was no substantial and consistent evidence to support duration of diabetes, systolic or diastolic blood pressure, total cholesterol, low- (LDL) and high- (HDL) density lipoproteins, gender, ethnicity, body mass index (BMI), socioeconomic status, or tobacco and alcohol consumption as being associated with incidence of PDR. There was insufficient evidence to evaluate prognostic factors associated with progression of PDR to HRC-PDR.  AUTHORS' CONCLUSIONS: Increased HbA1c is likely to be associated with progression to PDR; therefore, maintaining adequate glucose control throughout life, irrespective of stage of DR severity, may help to prevent progression to PDR and risk of its sight-threatening complications. Renal impairment in people with T1D or T2D, as well as younger age at diagnosis of diabetes mellitus (DM), increased triglyceride levels, and increased retinal venular diameters in people with T1D may also be associated with increased risk of progression to PDR. Given that more advanced DR severity is associated with higher risk of progression to PDR, the earlier the disease is identified, and the above systemic risk factors are controlled, the greater the chance of reducing the risk of PDR and saving sight.

Physical Activity and Risk of Major Diabetes-Related Complications in Individuals With Diabetes: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

Physical activity is a cornerstone in diabetes management; however, evidence synthesis on the association between physical activity and long-term diabetes-related complications is scarce.

PURPOSE

To summarize and evaluate findings on physical activity and diabetes-related complications, we conducted a systematic review and meta-analysis.

DATA SOURCES

We searched PubMed, Web of Science, and the Cochrane Library for articles published up to 6 July 2021.

STUDY SELECTION

We included prospective studies investigating the association between physical activity and incidence of and mortality from diabetes-related complications, i.e., cardiovascular disease (CVD), coronary heart disease, cerebrovascular events, heart failure, major adverse cardiovascular events, and microvascular complications such as retinopathy and nephropathy, in individuals with diabetes.

DATA EXTRACTION

Study characteristics and risk ratios with 95% CIs were extracted. Random-effects meta-analyses were performed, and the certainty of evidence and risk of bias were evaluated with use of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) and Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tools.

DATA SYNTHESIS

Overall, 31 studies were included. There was moderate certainty of evidence that high versus low levels of physical activity were inversely associated with CVD incidence, CVD mortality (summary risk ratio 0.84 [95% CI 0.77, 0.92], n = 7, and 0.62 [0.55, 0.69], n = 11), and microvascular complications (0.76 [0.67, 0.86], n = 8). Dose-response meta-analyses showed that physical activity was associated with lower risk of diabetes-related complications even at lower levels. For other outcomes, similar associations were observed but certainty of evidence was low or very low.

LIMITATIONS

Limitations include residual confounding and misclassification of exposure.

CONCLUSIONS

Physical activity, even below recommended amounts, was associated with reduced incidence of diabetes-related complications.

Weight Reduction as an Adjunctive Management Strategy for Diabetic Retinopathy

As rates of global obesity and diabetes increase, diabetic retinopathy continues to grow as a frequent cause of visual impairment. Despite tremendous recent strides in therapy, a significant fraction of patients remain poorly responsive to modern interventions. Adjunctive therapy in such settings could be widely beneficial. A growing body of evidence suggests that weight reduction strategies for obesity-related diabetes have the potential to serve as important supplements to modern ophthalmic care for preservation of vision.

Increasing metabolic variability increases the risk for vitrectomy in proliferative diabetic retinopathy

PURPOSE

Proliferative diabetic retinopathy (PDR) can be treated by retinal photocoagulation, but in some cases, the treatment is initiated too late or is insufficient so that the disease advances to a stage requiring vitrectomy. There is a need to identify risk factors that can predict if patients with PDR will develop complications in need for vitrectomy.

METHODS

Survival analysis with death as competing risk was used to study systemic risk factors for PDR progression to a complication in need for vitrectomy in right eyes of all 1288 diabetic patients from the Aarhus area, Denmark, who had developed proliferative retinopathy in the right eye during the 25 years period from 1 July 1994 until 1 July 2019.

RESULTS

The overall cumulative incidence of reaching a vitrectomy end point in the right eye was 24.1% (n = 311). In 9.3% (n = 120) of the patients where vitrectomy had been performed together with the first photocoagulation, the age of onset of diabetes was significantly higher (p < 0.0001), the diabetes duration longer (p < 0.035) and BMI higher (p < 0.01) than in the patients who had been vitrectomized later than the first photocoagulation. The risk for vitrectomy was significantly increased by high variability of HbA1c before the development of PDR (p < 0.0001), but not by other parameters known to increase the risk for developing PDR.

CONCLUSION

Increasing variability of HbA1c before the development of PDR increases the risk for progression to a complication in need of vitrectomy. The need for vitrectomy is unaffected by other risk factors known to increase the risk for developing PDR.

Effect of physical activity on reducing the risk of diabetic retinopathy progression: 10-year prospective findings from the 45 and Up Study

Objective

To examine the association of physical activities (PA) with diabetic retinopathy (DR) progression based on a 10-year follow-up of a large cohort of working-aged diabetic populations in Australia.

Methods

Nine thousand and eighteen working-aged diabetic patients were enrolled from the baseline of the 45 and Up Study from New South Wales, Australia. Self-reported PA collected by questionnaire at baseline in 2006 was graded into low (<5 sessions/week), medium (≥5–14), and high (≥14) levels. Retinal photocoagulation (RPC) treatment during the follow-up period was used as a surrogate for DR progression and was tracked through the Medicare Benefits Schedule, which was available from 2004 to 2016. Cox regression was used to estimate the association between PA and RPC incidence.

Results

In the fully adjusted model, higher PA level was significantly associated with a lower risk of RPC incident (Cox-regression, p-value for trend = 0.002; medium vs. low, hazard ratio (HR) = 0.78, 95% Confidence Interval (CI): 0.61–0.98; high vs. low, HR = 0.61, 95%CI: 0.36–0.84. In addition, gender, body mass index, insulin treatment, family history of diabetes, history of cardiovascular disease were significant effect modifiers for the association between PA and RPC.

Conclusions

Higher PA level was independently associated with a lower risk of DR progression among working-aged diabetic populations in this large cohort study.

Physical activity and risk of diabetic retinopathy: a systematic review and meta-analysis

AIMS

Diabetic retinopathy (DR) is an important microvascular complication of diabetes mellitus (DM) and a leading cause of visual impairment and blindness among people of working age. Physical activity (PA) or exercise is critical and beneficial for DM patients, whereas studies evaluating the relationship between PA and DR have yielded inconsistent and inconclusive results. The American Diabetes Association's "Standards of Medical Care in Diabetes" has also pointed out the indeterminate roles of PA in DR prevention. The purpose of this systematic review and meta-analysis was to explore the association between PA and DR risk.

METHODS

Medline (accessed by PubMed), EmBase, and Cochrane Library were systematically searched for studies up to June 2018, and the reference lists of the published articles were searched manually. The association between PA and DR risk was assessed using random-effect meta-analysis.

RESULTS

Twenty-two studies were included in this meta-analysis. PA was found to have a protective association with DR [risk ratio (RR) = 0.94, 95% confidence interval (95% CI) 0.90-0.98, p = 0.005] in diabetic patients, and the impact was more pronounced on vision-threatening DR (RR = 0.89, 95% CI 0.80-0.98, p = 0.02). Sedentary behavior could increase the risk of DR (RR = 1.18, 95% CI 1.01-1.37, p = 0.04). Moderate-intensity PA was likely to have a slight protective effect (RR = 0.76, 95% CI 0.58-1.00, p = 0.05).

CONCLUSION

PA is associated with lower DR risk, and more studies should focus on the causality between them.

Physical activity and eye diseases. The Beijing Eye Study

PURPOSE

To assess associations between the amount of physical activity and the prevalence of ocular diseases.

METHODS

The participants of the population-based Beijing Eye Study underwent a detailed ophthalmological examination and an interview. Physical activity was assessed in a standardized questionnaire.

RESULTS

Out of 3468 study participants, information on their physical activity was available for 3031 (87.4%) individuals (age: 64.6 ± 9.7 years; range: 50-93 years). In multivariate analysis (regression coefficient r: 0.41), higher physical activity was associated with a lower prevalence of diabetic retinopathy [p = 0.009; standardized regression coefficient beta: -0.05; non-standardized regression coefficient B: -15.7; 95% confidence interval (CI): -27.6, -3.90] after adjusting for younger age, rural region of habitation, lower level of education, lower blood concentrations of triglycerides and low-density lipoproteins and higher blood concentrations of high-density lipoproteins, higher systolic blood pressure, lower body mass index and lower depression score. Other major ocular diseases such as open-angle glaucoma (p = 0.25), angle-closure glaucoma (p = 0.59), nuclear cataract (p = 0.78), cortical cataract (p = 0.54), posterior subcapsular cataract (p = 0.96), retinal vein occlusions (p = 0.93) and central serous choroidopathy (p = 0.39) were not statistically associated with physical activity in that model. The association between higher physical activity and prevalence of age-related macular degeneration (p = 0.04; β: 0.04; B: 4.87; 95% CI: 0.25, 9.50) was marginally significant.

CONCLUSIONS

Higher physical activity and less sedentary lifestyle were associated with a lower prevalence of diabetic retinopathy, while the occurrence of other major ocular diseases such as any type of cataract and of glaucoma, retinal vein occlusions and central serous choroidopathy was statistically independent of physical activity or a more sedentary lifestyle.

Review of the literature examining the association between physical activity and retinopathy

The main aim of this review was to evaluate the association between physical activity and retinopathy. Secondary aims included evaluating the association between sedentary behavior and retinopathy, and evaluating the association between physical activity/sedentary behavior on health outcomes among patients with existing retinopathy. Twenty-one articles met our criteria for inclusion in this review. Among the 19 studies evaluating the main aim (physical activity and retinopathy), 53% (n = 10/19) demonstrated evidence of a favorable (inverse) association between physical activity and retinopathy, 42% (n = 8/19) reported a null association physical activity and retinopathy, and 5% (n = 1/19) presented evidence for a detrimental association between physical activity and retinopathy. Regarding the secondary aims, one study demonstrated a detrimental association between sedentary behavior and retinopathy. Similarly, one study demonstrated that physical activity was protective against early mortality among those with mild retinopathy. This review identifies an 'indeterminate' association between physical activity and retinopathy. Too few studies evaluated the association between sedentary behavior and retinopathy or the effects of physical activity on health outcomes among those with existing retinopathy.

The association between bouted and non-bouted physical activity on retinopathy prevalence

OBJECTIVE

We evaluated the specific differential association between non-bouted, lifestyle physical activities (vs. structured exercise; i.e., bouted physical activity) on retinopathy prevalence among a national sample of the broader U.S. adult population.

METHODS

Data from the 2005-2006 National Health and Nutrition Examination Survey (NHANES) was used to identify 1501 adults, between 40 and 85years. Bouted and non-bouted physical activities were assessed using objective accelerometer monitoring. A 10-minute bout was defined as 10+ consecutive minutes above the moderate-to-vigorous physical activity (MVPA) cut-point, with the allowance of 1-2-minute interruption intervals. Non-bout MVPA was determined by the number of MVPA minutes not accrued in a bout. Participants were screened for non-proliferative retinopathy using Early Treatment Diabetic Retinopathy Study grading criteria, as well as objective retinal imaging assessments using the Canon Non-Mydriatic Retinal Camera CR6-45NM. Individuals were excluded if they had been diagnosed with coronary artery disease, congestive heart failure, heart attack or stroke.

RESULTS

Participants with worse retinopathy engaged in less bouted and non-bouted physical activity, had a higher BMI and were more likely to have diabetes and hypertension. For every 1min/day increase in non-bouted MVPA, participants had a 7% reduced odds of moderate-to-severe retinopathy compared to no retinopathy (OR=0.93; 95% CI: 0.87-0.99; P=0.04); results were similar in an unadjusted model (OR=0.93; 95% CI: 0.89-0.97; P=0.007). Bouted MVPA was not associated with retinopathy prevalence in the multivariate model.

CONCLUSION

In this nationally representative sample of adults, those who engaged in non-bouted physical activity had reduced odds of a diagnosis of moderate-to-severe retinopathy.

Higher levels of physical activity are independently associated with a lower incidence of diabetic retinopathy in Japanese patients with type 2 diabetes: A prospective cohort study, Diabetes Distress and Care Registry at Tenri (DDCRT15)

We assessed the prospective association between baseline levels of physical activity (PA) and the incidence of newly developed diabetic retinopathy (DR) in patients with type 2 diabetes. Data from 1,814 patients with type 2 diabetes without DR were obtained from a Japanese diabetes registry at Tenri Hospital, Nara, Japan. To assess the independent correlations between baseline PA levels and newly developed DR, the participants were divided into five categories based on their PA levels. A Cox proportional hazards model with time-varying exposure information was used and adjusted for potential confounders to assess the independent correlations. At baseline, the mean age, BMI, and hemoglobin A1c levels of the patients were 65.5 years, 24.5 kg/m2, and 7.2% (54 mmol/mol), respectively. After 2 years, newly developed DR was confirmed in 184 patients (10.1%). Patients with newly developed DR had longer duration of type 2 diabetes (14.7 versus 11.0 years, p < 0.0001), higher systolic blood pressure (139.2 versus 135.1 mmHg, p = 0.0012), lower estimated glomerular filtration rate (74.0 versus 77.1 mL/min/1.73 m2, p = 0.0382), greater urinary albumin-creatinine ratio (4.00 versus 2.45 mg/mmol, p < 0.0039), and higher HbA1c levels (7.5 versus 7.2%, p = 0.0006) than those without newly developed DR. The multivariable-adjusted hazard ratios for DR development were 0.87 (95% CI, 0.53-1.40; p = 0.557), 0.83 (95% CI, 0.52-1.31; p = 0.421), 0.58 (95% CI, 0.35-0.94; p = 0.027), and 0.63 (95% CI, 0.42-0.94; p = 0.025)for the second, third, fourth, and fifth PA categories, respectively, compared with the reference category of patients with a mean PA of 0 metabolic equivalent of task-hours/week). Higher PA levels are independently associated with a lower incidence of DR in Japanese patients with type 2 diabetes.

The relation between exercise and glaucoma in a South Korean population-based sample

Purpose

To investigate the association between exercise and glaucoma in a South Korean population-based sample.

Design

Population-based, cross-sectional study.

Participants

A total of 11,246 subjects, 40 years and older who underwent health care assessment as part of the 2008–2011 Korean National Health and Nutrition Examination Survey.

Methods

Variables regarding the duration (total minutes per week), frequency (days per week), and intensity of exercise (vigorous, moderate exercise and walking) as well as glaucoma prevalence were ascertained for 11,246 survey participants. Demographic, comorbidity, and health-related behavior information was obtained via interview. Multivariable logistic regression analyses were performed to determine the association between the exercise-related parameters and odds of a glaucoma diagnosis.

Main outcome measure(s)

Glaucoma defined by International Society for Geographical and Epidemiological Ophthalmology criteria.

Results

Overall, 336 (2.7%) subjects met diagnostic criteria for glaucomatous disease. After adjustment for potential confounding variables, subjects engaged in vigorous exercise 7 days per week had higher odds of having glaucoma compared with those exercising 3 days per week (Odds Ratio [OR] 3.33, 95% confidence interval [CI] 1.16–9.54). High intensity of exercise, as categorized by the guidelines of the American College of Sports Medicine (ACSM), was also associated with greater glaucoma prevalence compared with moderate intensity of exercise (OR 1.55, 95% CI 1.03–2.33). There was no association between other exercise parameters including frequency of moderate exercise, walking, muscle strength exercise, flexibility training, or total minutes of exercise per week, and the prevalence of glaucoma. In sub-analyses stratifying by gender, the association between frequency of vigorous exercise 7 days per week and glaucoma diagnosis remained significant in men (OR 6.05, 95% CI 1.67–21.94) but not in women (OR 0.96 95% CI: 0.23–3.97). A U-shaped association between exercise intensity and glaucoma prevalence was noted in men (OR 1.71, 95% CI 1.09–2.69 for low intensity versus moderate intensity; OR 2.19, 95% CI 1.25–3.85 for high intensity versus moderate intensity).

Conclusion

In a South Korean population sample, daily vigorous exercise was associated with higher glaucoma prevalence. In addition, the intensity of exercise was positively associated with glaucoma diagnosis in men but not women.

Review: Helping the athlete with type 1 diabetes

Exercise is a significant physiological challenge with markedly increased cardiac output, respiration and fuel mobilisation. Whilst the cardio-respiratory response to exercise is similar in type 1 diabetes to that seen in non-diabetic subjects, the response to mobilisation of fuel source to support exercise is impaired. This effect, when combined with the difficulties of nutrition and insulin therapy in type 1 diabetes may negatively impact on the performance of the athlete with diabetes. Hypoglycaemia both during and following exercise, is a significant risk. Furthermore, hyperglycaemia prior to and following some types of exercises can also be problematic. The effect on blood glucose of varying sports can be predicted, and therefore, pro-active adjustments of insulin therapy and nutrition can be made. This article outlines the important differences seen with exercise in type 1 diabetes and discusses appropriate strategies to normalise performance and reduce the risk of hypoglycaemia.

The influence of physical activity on vascular complications and mortality in patients with type 2 diabetes mellitus

AIMS

There is limited evidence regarding the association between physical activity and vascular complications, particularly microvascular disease, in patients with type 2 diabetes.

METHODS

From the 11 140 patients in the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron modified release Controlled Evaluation) trial, the effect of physical activity, categorized as none, mild, moderate or vigorous, and the number of sessions within a week, was examined in multivariable regression models adjusted for potential confounders. The study end-points were major cardiovascular events, microvascular complications and all-cause mortality.

RESULTS

Forty-six percent of participants reported undertaking moderate to vigorous physical activity for >15 min at least once in the previous week. During a median of 5 years of follow-up, 1031 patients died, 1147 experienced a major cardiovascular event and 1136 a microvascular event. Compared to patients who undertook no or mild physical activity, those reporting moderate to vigorous activity had a decreased risk of cardiovascular events (HR: 0.78, 95% CI: 0.69-0.88, p < 0.0001), microvascular events (HR: 0.85, 95% CI: 0.76-0.96, p = 0.010) and all-cause mortality (HR: 0.83, 95% CI: 0.73-0.94, p = 0.0044).

CONCLUSIONS

Moderate to vigorous, but not mild, physical activity is associated with a reduced incidence of cardiovascular events, microvascular complications and all-cause mortality in patients with type 2 diabetes.

Intense physical activity is associated with better metabolic control in patients with type 1 diabetes

OBJECTIVES

To analyze the association between adherence to physical activity guideline recommendations and metabolic control in patients with type 1 diabetes (DM1).

METHODS

An observational, cross-sectional study was conducted in 130 adult DM1 patients from Spain with a mean age of 33.9±11.5 years and disease duration of 16.5±9.5 years. We analyzed several clinical, anthropometric and laboratory variables together with information obtained from the Minnesota Leisure Time Physical Activity Questionnaire.

RESULTS

Evaluated patients reported an average of 850.6±493.2min of physical activity per week, being classified as light (567.4±425.4min/week), moderate (169.9±212.1min/week) and intense activities (120.6±184.2). Patients who dedicated more time to intense physical activity were younger, had university studies and were males more often than those who spent none or less time on intense physical activity. We observed no differences in HbA1c levels in relation to time dedicated to moderate physical activities. However, patients who dedicated more than 150min to intense physical activity per week had lower levels of HbA1c (HbA1c: 7.2±1.0% versus 7.8±1.1% versus 8.0±1.0% in more than 149min, between 0 and 149min or 0min of intense physical activity per week, respectively).

CONCLUSION

Performing more than 150min of intense physical activity a week is associated with better metabolic control in type 1 Spanish patients. No positive impact in metabolic control was observed in relation to the time spent in moderate physical activity.

Physical activity and type 2 diabetes. Recommandations of the SFD (Francophone Diabetes Society) diabetes and physical activity working group

Although regular physical activity is an integral part of T2D management, few diabetic patients have a sufficient level of physical activity. However over the past decade or so, the beneficial effects of regular physical activity have been well demonstrated, both in T2D prevention (50% reduction in the incidence of T2D in subjects with high metabolic risk) as well as T2D management for the improvement of glycaemic control (mean 0.7% improvement of HbA1c) and the reduction of T2D-related comorbidities (improvement in blood pressure values and lipid profile, decrease in insulin resistance). Physical activity has both acute effects (effects of one exercise session) and more prolonged effects of exercise when it is repeated on a regular basis (training effect). In addition, the physical activity recommendations have been extended to a wide range of physical activities (by combining both endurance and muscle strengthening exercises), thus varying the physical activity practiced according to the patient's available time, practice sites, preferences and interests. Following a pathophysiology review, the effects of physical activity will be discussed and presented in terms of evidence-based medicine. The recommendations will be defined and practical prescribing information will be suggested, while taking into account that clinicians are concerned with answering questions regarding how, where and with whom: how can patients be motivated to practice a physical activity over the long-term? And how can qualified exercise trainers and appropriate practice settings be found?

Organ-based response to exercise in type 1 diabetes

While significant research has clearly identified sedentary behavior as a risk factor for type 2 diabetes and its subsequent complications, the concept that inactivity could be linked to the complications associated with type 1 diabetes (T1D) remains underappreciated. This paper summarizes the known effects of exercise on T1D at the tissue level and focuses on the pancreas, bone, the cardiovascular system, the kidneys, skeletal muscle, and nerves. When possible, the molecular mechanisms underlying the benefits of exercise for T1D are elucidated. The general benefits of increased activity on health and the barriers to increased exercise specific to people with T1D are discussed.

Evidence-based risk assessment and recommendations for physical activity clearance: diabetes mellitus and related comorbidities1This paper is one of a selection of papers published in this Special Issue, entitled Evidence-based risk assessment and recommendations for physical activity clearance, and has undergone the Journal’s usual peer review process

Physical activity (PA) is one of the most powerful treatment options for persons with prediabetes or diabetes. However, some elevation in risk occurs with increased PA, at least initially, and certain precautions need to be made to lower these risks, particularly if these persons are unaccustomed to exercise. We conducted a standardized search of all adverse events associated with increased PA in persons with prediabetes or diabetes (type 1 or type 2) and provided evidence-based guidelines on PA screening in these apparently high-risk individuals. A systematic literature review was performed of all studies reporting on adverse events in persons with prediabetes or diabetes. Studies included were from all designs (retrospective and prospective including randomized controlled trials) and were assessed according to evaluation criteria adapted by a consensus panel. A total of 47 studies, involving >8000 individuals, were deemed eligible. A number of these studies identified a range of mild to severe acute risks with exercise (musculoskeletal injury, hypoglycemia, foot ulceration, proliferative retinopathy, hypotension, sudden death) but the overall prevalence was low. Based on several randomized controlled trials and prospective studies in which prescribed exercise was performed at a wide range of intensities, it appears that increased PA is a relatively safe procedure with no evidence of a loss of life. Based on our assessment of the available literature, we provide a new PA risk algorithm for persons with prediabetes and diabetes and comment on the role of the patient, the qualified exercise professional, and the patient’s physician in the risk screening process.

Association between physical activity and retinal microvascular signs: the Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To examine the association between physical activity measured during leisure, sport, and work and retinal microvascular signs.

METHODS

Participants of the Atherosclerosis Risk in Communities (ARIC) Study, a population-based cross-sectional study, had retinal photographs taken at their third follow up visit (1993-1995). Retinal microvascular signs were assessed using a standardized protocol and retinal vascular caliber by a computer-assisted method. Leisure, sport, and work-related physical activity levels were determined through a modified Baecke physical activity questionnaire.

RESULTS

A higher level of physical activity during sport and work was significantly associated with a lower prevalence of arteriovenous (AV) nicking, wider venular caliber, and retinopathy. In multivariate models, persons with a level of sport-related physical activity above the median were less likely to have AV nicking (odds ratio [OR] = 0.87; 95% confidence interval [CI] 0.78-0.97) and wider retinal venules (OR = 0.91; 95% CI: 0.83-0.99). Persons with a level of work-related physical activity above the median were less likely to have diabetic retinopathy (OR = 0.66, 95% CI: 0.51-0.85).

CONCLUSIONS

In this cross-sectional analyzes, higher levels of physical activity was associated with a lower prevalence of retinal microvascular abnormalities.

[Impact of physical activity on metabolic control and the development of chronic complications in patients with type 1 diabetes mellitus]

Together with a balanced diet, regular physical activity is one of the pillars of diabetes mellitus (DM) management. Physical activity theoretically provides the same advantages in people with DM as in the general population and also has some beneficial effects in controlling metabolic factors, such as improving blood glucose levels and insulin sensitivity. In this article, we analyze the main clinical studies published to date that evaluate the impact of physical activity on metabolic control or the development of chronic complications in patients with type 1 diabetes mellitus. In conclusion, most of the evaluated studies show that regular physical activity favorably affects metabolic control in DM (or at least does not have adverse effects). However, there is insufficient information about the impact of physical activity on the development and progression of chronic complications.

Diabetes in sports

CONTEXT

Exercise is recommended for individuals with diabetes mellitus, and several facets of the disease must be considered when managing the diabetic athlete. The purpose of this article is to review diabetes care in the context of sports participation.

EVIDENCE ACQUISITION

Relevant studies were identified through a literature search of MEDLINE and the Cochrane database, as well as manual review of reference lists of identified sources.

RESULTS

Diabetics should be evaluated for complications of long-standing disease before beginning an exercise program, and exercise should be modified appropriately if complications are present. Athletes who use insulin or oral insulin secretogogues are at risk for exercise-induced immediate or delayed hypoglycemia. Diabetics are advised to engage in a combination of regular aerobic and resistance exercise. Insulin-dependent diabetics should supplement carbohydrate before and after exercise, as well as during exercise for events lasting longer than 1 hour. Adjustment of insulin dosing based on planned exercise intensity is another strategy to prevent hypoglycemia. Insulin-dependent athletes should monitor blood sugar closely before, during, and after exercise. Significant hyperglycemia before exercise should preclude exercise because the stress of exercise can paradoxically exacerbate hyperglycemia and lead to ketoacidosis. Athletes should be aware of hypoglycemia symptoms and have rapidly absorbable glucose available in case of hypoglycemia.

CONCLUSION

Exercise is an important component of diabetes treatment, and most people with diabetes can safely participate in sports at recreational and elite levels with attention to appropriate precautions.

Battling insulin resistance in elderly obese people with type 2 diabetes: bring on the heavy weights

Exercise improves insulin resistance and has beneficial effects in preventing and treating type 2 diabetes. However, aerobic exercise is hindered in many type 2 diabetic patients because of advancing age, obesity, and other comorbid conditions. Weight lifting or progressive resistance training (PRT) offers a safe and effective exercise alternative for these people. PRT promotes favorable energy balance and reduced visceral fat deposition through enhanced basal metabolism and activity levels while counteracting age- and disease-related muscle wasting. PRT improves insulin sensitivity and glycemic control; increases muscle mass, strength, and endurance; and has positive effects on bone density, osteoarthritic symptoms, mobility impairment, self-efficacy, hypertension, and lipid profiles. PRT also alleviates symptoms of anxiety, depression, and insomnia in individuals with clinical depression and improves exercise tolerance in individuals with cardiac ischemic disease and congestive heart failure; all of these aspects are relevant to the care of diabetic elders. Moreover, PRT is safe and well accepted in many complex patient populations, including very frail elderly individuals and those with cardiovascular disease. The greater feasibility of using PRT over aerobic exercise in elderly obese type 2 diabetic individuals because of concomitant cardiovascular, arthritic, and other disease provides a solid rationale for investigating the global benefits of PRT in the management of diabetes.

Systemic considerations in the management of diabetic retinopathy

PURPOSE

To highlight the systemic factors which affect onset and/or progression of diabetic retinopathy (DR) and to emphasize the role and responsibilities of ophthalmologists and other eye care providers to ensure that appropriate systemic medical evaluation of the patient with diabetes is being pursued.

DESIGN

Literature review of publications relevant to diabetic retinopathy, blood glucose control, diabetes mellitus type, hypertension, renal disease, elevated serum lipids, exercise, pregnancy, anticoagulation, thrombolysis, smoking, anemia and antioxidant ingestion.

FINDINGS

Intensive blood glucose control and control of systemic hypertension reduce the risk of new onset DR and slow the progression of existing DR. Severe DR may be an indicator of renal disease while severe renal disease and its treatment can affect the progression of DR. Elevated serum lipids are associated with macular exudate and moderate visual loss. Certain types of excessive exercise in patients with advanced stages of retinopathy may aggravate vitreous hemorrhage. During pregnancy, DR should be monitored closely as transient progression of DR can occur. Therapeutic anticoagulation and thrombolysis are not contraindicated at any stage of DR. Anemia can result in progression of DR, smoking in general should be discouraged, and the role of antioxidant therapy requires further study.

CONCLUSIONS

Blindness from diabetic retinopathy is now largely preventable with timely detection and appropriate interventional therapy. Routine, repetitive, lifelong, expert clinical retinal examination is essential for the fundamental ophthalmic care of the patient with diabetes. However, diabetes mellitus is a systemic disease and thus optimal ophthalmic care must include diligent evaluation and treatment of concomitant systemic disorders that influence the development, progression and ultimate outcome of diabetic retinopathy. Optimization of these systemic considerations through an intensive, multi-disciplinary, healthcare team-based approach will maximize the ophthalmic and general health of these patients. Ophthalmologists and other eye care providers are critical members of this team with unique responsibilities to ensure that appropriate systemic medical evaluation is being pursued.