Diabetic neuropathy in elderly Type 2 diabetic patients: effects of insulin treatment

Painful forms of diabetic neuropathy

Diabetic neuropathy is a frequent and severe degenerative complication of diabetes. The diagnosis is easily performed in painful symptomatic patients. Sensitivity disorders responsible for numbness, tingling, and loss of feeling are part and parcel of diabetic foot syndrome and require investigation in view of preventing trophic ulcers. To date, there exists no specific treatment for diabetic neuropathy possibly preventable by careful control of metabolic disorder. Effective management of diabetic patients would make it possible to limit the dramatic consequences of diabetic neuropathy while at the same time acting on other complications.

The foot in diabetes - a reminder of an ever-present risk

The term 'diabetic foot disease' (DFD) often signifies the presence of foot ulceration and infection, but one must also be wary of the rarer occurrence of Charcot foot disease. The worldwide prevalence of DFD is 6.3% (95%CI: 5.4-7.3%). Foot complications present a major challenge to both patients and healthcare systems, with increased rates of hospitalisation and an almost trebled 5-year mortality. The Charcot foot often occurs in patients with long-standing diabetes, presenting as an inflamed or swollen foot or ankle, following unrecognised minor trauma. This review focuses on the prevention and early identification of the 'at-risk' foot. DFD is best managed by a multi-disciplinary foot clinic team consisting of podiatrists and healthcare professionals. This ensures a combination of expertise and provision of a multi-faceted evidence-based treatment plan. Current research using endothelial progenitor cells (EPC) and mesenchymal stem cells (MSC) offers a new dimension in wound management.

Peripheral Neuropathy and All-Cause and Cardiovascular Mortality in U.S. Adults : A Prospective Cohort Study

BACKGROUND

Growing evidence indicates that peripheral neuropathy (PN) is common even in the absence of diabetes. However, the clinical sequelae of PN have not been quantified in the general population.

OBJECTIVE

To assess the associations of PN with all-cause and cardiovascular mortality in the general adult population of the United States.

DESIGN

Prospective cohort study.

SETTING

NHANES (National Health and Nutrition Examination Survey), 1999 to 2004.

PARTICIPANTS

7116 adults aged 40 years or older who had standardized monofilament testing for PN.

MEASUREMENTS

Cox regression to evaluate the associations of PN with all-cause and cardiovascular mortality after adjustment for demographic and cardiovascular risk factors, overall and stratified by diabetes status.

RESULTS

The overall prevalence of PN (±SE) was 13.5% ± 0.5% (27.0% ± 1.4% in adults with diabetes and 11.6% ± 0.5% in adults without diabetes). During a median follow-up of 13 years, 2128 participants died, including 488 of cardiovascular causes. Incidence rates (per 1000 person-years) of all-cause mortality were 57.6 (95% CI, 48.4 to 68.7) in adults with diabetes and PN, 34.3 (CI, 30.3 to 38.8) in adults with PN but no diabetes, 27.1 (CI, 23.4 to 31.5) in adults with diabetes but no PN, and 13.0 (CI, 12.1 to 14.0) in adults with no diabetes and no PN. In adjusted models, PN was significantly associated with all-cause mortality (hazard ratio [HR], 1.49 [CI, 1.15 to 1.94]) and cardiovascular mortality (HR, 1.66 [CI, 1.07 to 2.57]) in participants with diabetes. In those without diabetes, PN was significantly associated with all-cause mortality (HR, 1.31 [CI, 1.15 to 1.50]), but the association between PN and cardiovascular mortality was not statistically significant after adjustment (HR, 1.27 [CI, 0.98 to 1.66]).

LIMITATION

Prevalent cardiovascular disease was self-reported, and PN was defined by monofilament testing only.

CONCLUSION

Peripheral neuropathy was common and was independently associated with mortality in the U.S. population, even in the absence of diabetes. These findings suggest that decreased sensation in the foot may be an underrecognized risk factor for death in the general population.

PRIMARY FUNDING SOURCE

National Institute of Diabetes and Digestive and Kidney Diseases and National Heart, Lung, and Blood Institute of the National Institutes of Health.

Epidemiology of Peripheral Neuropathy and Lower Extremity Disease in Diabetes

PURPOSE OF REVIEW

Diabetic peripheral neuropathy eventually affects nearly 50% of adults with diabetes during their lifetime and is associated with substantial morbidity including pain, foot ulcers, and lower limb amputation. This review summarizes the epidemiology, risk factors, and management of diabetic peripheral neuropathy and related lower extremity complications.

RECENT FINDINGS

The prevalence of peripheral neuropathy is estimated to be between 6 and 51% among adults with diabetes depending on age, duration of diabetes, glucose control, and type 1 versus type 2 diabetes. The clinical manifestations are variable, ranging from asymptomatic to painful neuropathic symptoms. Because of the risk of foot ulcer (25%) and amputation associated with diabetic peripheral neuropathy, aggressive screening and treatment in the form of glycemic control, regular foot exams, and pain management are important. There is an emerging focus on lifestyle interventions including weight loss and physical activity as well. The American Diabetes Association has issued multiple recommendation statements pertaining to diabetic neuropathies and the care of the diabetic foot. Given that approximately 50% of adults with diabetes will be affected by peripheral neuropathy in their lifetime, more diligent screening and management are important to reduce the complications and health care burden associated with the disease.

Metformin attenuates increase of synaptic number in the rat spinal dorsal horn with painful diabetic neuropathy induced by type 2 diabetes: a stereological study

In our previous study, we have shown that number of synapses in the L5 segment of spinal dorsal horn increased significantly in a rat model of painful diabetic neuropathy (PDN) induced by high-dose of streptozotocin (an animal model of type 1 diabetes). The aims of this study were: (1) to determine whether high fat diet/low dose streptozotocin-diabetes, a rat model for type 2 diabetes, related PDN was also associated with this synaptic plasticity, (2) to reveal the range of this synaptic plasticity change occurred (in the whole length of spinal dorsal horn or only in the L5 lumbar segment of spinal dorsal horn) and (3) to discover whether treatment with metformin had effect on this synaptic plasticity. Male adult Sprague-Dawley rats were randomly allocated into the control group (n = 7), the PDN group (n = 6) and the PDN treated with metformin (PDN + M) group (n = 7), respectively. 28 days after medication, synaptic and neuronal numbers in the whole length of spinal dorsal horn or in 1 mm length of the L5 segment of spinal dorsal horn were estimated by the optical disector (a stereological technique). Compared to the control group and the PDN + M group, number of synapses in the L5 segment of spinal dorsal horn increased significantly in the PDN group (P < 0.05). There was no significant change between the control group and the PDN + M group in terms of the parameters in the L5 segment of the spinal dorsal horn (P > 0.05). Parameters of the whole length of spinal dorsal horn showed no significant changes (P > 0.05). Our results suggest that high fat diet/low dose streptozotocin diabetes related PDN is also associated with a numerical increase of synapses in the L5 segment of spinal dorsal horn but not in the whole length of spinal dorsal horn. Furthermore, the analgesic effect of metformin against PDN is related to its inhibition of numerical increase of synaptic number in the rat spinal dorsal horn.

Current Ideas on the Treatment Of Diabetic Neuropathies

Diabetic neuropathies are common and their prevalence is rising with the growth in the global prevalence of type 2 diabetes. Several patterns of neuropathy have now been described, with diabetic sensorimotor polyneuropathy (DPN) being the most common. Autonomic neuropathy, entrapment neuropathies including carpal tunnel syndrome and ulnar neuropathy at the elbow pose additional burdens. DPN can be detected in over half of all diabetic subjects and approximately 20% of all patients with DPN also experience neuropathic pain, a complication with major impacts on quality of life. Currently, the only available treatments for DPN are optimal glucose control and pain management, whereas interventions, beyond optimizing hyperglycemic control, to address the underlying polyneuropathy are not available. Here we review current treatment options and new literature relating to DPN, with an emphasis on novel and emerging treatments.

WITHDRAWN: Sulphonylurea monotherapy for patients with type 2 diabetes mellitus

The Cochrane Metabolic and Endocrine Disorders Group withdrew this review as of Issue 7, 2015 because of the involvement of one author (SS Lund) being employed in a pharmaceutical company. The authors of the review and the Cochrane Metabolic and Endocrine Disorders Group did not find that this was a breach of the rules of the Cochrane Collaboration at the time when it was published. However, after the publication of the review, the Cochrane Collaboration requested withdrawal of the review due to the employment of the author. A new protocol for a review to cover this topic will be published. This will have a new title and a markedly improved protocol fulfilling new and important developments and standards within the Cochrane Collaboration as well as an improved inclusion and search strategy making it necessary to embark on a completely new review project.

The editorial group responsible for this previously published document have withdrawn it from publication.

Sulphonylurea monotherapy for patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a growing health problem worldwide. Whether sulphonylureas show better, equal or worse therapeutic effects in comparison with other antidiabetic interventions for patients with T2DM remains controversial.

OBJECTIVES

To assess the effects of sulphonylurea monotherapy versus placebo, no intervention or other antidiabetic interventions for patients with T2DM.

SEARCH METHODS

We searched publications in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, LILACS and CINAHL (all until August 2011) to obtain trials fulfilling the inclusion criteria for our review.

SELECTION CRITERIA

We included clinical trials that randomised patients 18 years old or more with T2DM to sulphonylurea monotherapy with a duration of 24 weeks or more.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias. The primary outcomes were all-cause and cardiovascular mortality. Secondary outcomes were other patient-important outcomes and metabolic variables. Where possible, we used risk ratios (RR) with 95% confidence intervals (95% CI) to analyse the treatment effect of dichotomous outcomes. We used mean differences with 95% CI to analyse the treatment effect of continuous outcomes. We evaluated the risk of bias. We conducted trial sequential analyses to assess whether firm evidence could be established for a 10% relative risk reduction (RRR) between intervention groups.

MAIN RESULTS

We included 72 randomised controlled trials (RCTs) with 22,589 participants; 9707 participants randomised to sulphonylureas versus 12,805 participants randomised to control interventions. The duration of the interventions varied from 24 weeks to 10.7 years. We judged none of the included trials as low risk of bias for all bias domains. Patient-important outcomes were seldom reported.First-generation sulphonylureas (FGS) versus placebo or insulin did not show statistical significance for all-cause mortality (versus placebo: RR 1.46, 95% CI 0.87 to 2.45; P = 0.15; 2 trials; 553 participants; high risk of bias (HRB); versus insulin: RR 1.18, 95% CI 0.88 to 1.59; P = 0.26; 2 trials; 1944 participants; HRB). FGS versus placebo showed statistical significance for cardiovascular mortality in favour of placebo (RR 2.63, 95% CI 1.32 to 5.22; P = 0.006; 2 trials; 553 participants; HRB). FGS versus insulin did not show statistical significance for cardiovascular mortality (RR 1.36, 95% CI 0.68 to 2.71; P = 0.39; 2 trials; 1944 participants; HRB). FGS versus alpha-glucosidase inhibitors showed statistical significance in favour of FGS for adverse events (RR 0.63, 95% CI 0.52 to 0.76; P = 0.01; 2 trials; 246 participants; HRB) and for drop-outs due to adverse events (RR 0.28, 95% CI 0.12 to 0.67; P = 0.004; 2 trials; 246 participants; HRB).Second-generation sulphonylureas (SGS) versus metformin (RR 0.98, 95% CI 0.61 to 1.58; P = 0.68; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 0.92, 95% CI 0.60 to 1.41; P = 0.70; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.79 to 1.18; P = 0.72; 4 trials; 1642 participants; HRB), meglitinides (RR 1.44, 95% CI 0.47 to 4.42; P = 0.52; 7 trials; 2038 participants; HRB), or incretin-based interventions (RR 1.39, 95% CI 0.52 to 3.68; P = 0.51; 2 trials; 1503 participants; HRB) showed no statistically significant effects regarding all-cause mortality in a random-effects model. SGS versus metformin (RR 1.47; 95% CI 0.54 to 4.01; P = 0.45; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 1.30, 95% CI 0.55 to 3.07; P = 0.55; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.73 to 1.28; P = 0.80; 4 trials; 1642 participants; HRB) or meglitinide (RR 0.97, 95% CI 0.27 to 3.53; P = 0.97; 7 trials, 2038 participants, HRB) showed no statistically significant effects regarding cardiovascular mortality. Mortality data for the SGS versus placebo were sparse. SGS versus thiazolidinediones and meglitinides did not show statistically significant differences for a composite of non-fatal macrovascular outcomes. SGS versus metformin showed statistical significance in favour of SGS for a composite of non-fatal macrovascular outcomes (RR 0.67, 95% CI 0.48 to 0.93; P = 0.02; 3018 participants; 3 trials; HRB). The definition of non-fatal macrovascular outcomes varied among the trials. SGS versus metformin, thiazolidinediones and meglitinides showed no statistical significance for non-fatal myocardial infarction. No meta-analyses could be performed for microvascular outcomes. SGS versus placebo, metformin, thiazolidinediones, alpha-glucosidase inhibitors or meglitinides showed no statistical significance for adverse events. SGS versus alpha-glucosidase inhibitors showed statistical significance in favour of SGS for drop-outs due to adverse events (RR 0.48, 95% CI 0.24 to 0.96; P = 0.04; 9 trials; 870 participants; HRB). SGS versus meglitinides showed no statistical significance for the risk of severe hypoglycaemia. SGS versus metformin and thiazolidinediones showed statistical significance in favour of metformin (RR 5.64, 95% CI 1.22 to 26.00; P = 0.03; 4 trials; 3637 participants; HRB) and thiazolidinediones (RR 6.11, 95% CI 1.57 to 23.79; P = 0.009; 6 trials; 5660 participants; HRB) for severe hypoglycaemia.Third-generation sulphonylureas (TGS) could not be included in any meta-analysis of all-cause mortality, cardiovascular mortality or non-fatal macro- or microvascular outcomes. TGS versus thiazolidinediones showed statistical significance regarding adverse events in favour of TGS (RR 0.88, 95% CI 0.78 to 0.99; P = 0.03; 3 trials; 510 participants; HRB). TGS versus thiazolidinediones did not show any statistical significance for drop-outs due to adverse events. TGS versus other comparators could not be performed due to lack of data.For the comparison of SGS versus FGS no meta-analyses of all-cause mortality, cardiovascular mortality, non-fatal macro- or microvascular outcomes, or adverse events could be performed.Health-related quality of life and costs of intervention could not be meta-analysed due to lack of data.In trial sequential analysis, none of the analyses of mortality outcomes, vascular outcomes or severe hypoglycaemia met the criteria for firm evidence of a RRR of 10% between interventions.

AUTHORS' CONCLUSIONS

There is insufficient evidence from RCTs to support the decision as to whether to initiate sulphonylurea monotherapy. Data on patient-important outcomes are lacking. Therefore, large-scale and long-term randomised clinical trials with low risk of bias, focusing on patient-important outcomes are required.

Enhanced glucose control for preventing and treating diabetic neuropathy

BACKGROUND

There are two types of diabetes. Type 1 diabetes affects younger people and needs treatment with insulin injections. Type 2 diabetes affects older people and can usually be treated by diet and oral drugs. Diabetic neuropathy affects 10% of patients with diabetes mellitus at diagnosis and 40% to 50% after 10 years. Enhanced glucose control is the best studied intervention for the prevention of this disabling condition but there have been no systematic reviews of the evidence.

OBJECTIVES

To examine the evidence for enhanced glucose control in the prevention of distal symmetric polyneuropathy in people with type 1 and type 2 diabetes.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register (30 January 2012), CENTRAL (2012, Issue 1), MEDLINE (1966 to January 2012) and EMBASE (1980 to January 2012) for randomized controlled trials of enhanced glucose control in diabetes mellitus.

SELECTION CRITERIA

We included all randomized, controlled studies investigating enhanced glycemic control that reported neuropathy outcomes after at least one year of intervention. Our primary outcome measure was annual development of clinical neuropathy defined by a clinical scale. Secondary outcomes included motor nerve conduction velocity and quantitative vibration testing. 

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed all titles and abstracts identified by the database searches for inclusion. Two authors abstracted data from all included studies with a standardized form. A third author mediated conflicts. We analyzed the presence of clinical neuropathy with annualized risk differences (RDs), and conduction velocity and quantitative velocity measurements with mean differences per year. 

MAIN RESULTS

This review identified 17 randomized studies that addressed whether enhanced glucose control prevents the development of neuropathy. Seven of these studies were conducted in people with type 1 diabetes, eight in type 2 diabetes, and two in both types. A meta-analysis of the two studies that reported the primary outcome (incidence of clinical neuropathy) with a total of 1228 participants with type 1 diabetes revealed a significantly reduced risk of developing clinical neuropathy in those with enhanced glucose control, an annualized RD of -1.84% (95% confidence interval (CI) -1.11 to -2.56). In a similar analysis of four studies that reported the primary outcome, involving 6669 participants with type 2 diabetes, the annualized RD of developing clinical neuropathy was -0.58% (95% CI 0.01 to -1.17). Most secondary outcomes were significantly in favor of intensive treatment in both populations. However, both types of diabetic participants also had a significant increase in severe adverse events including hypoglycemic events.

AUTHORS' CONCLUSIONS

According to high-quality evidence, enhanced glucose control significantly prevents the development of clinical neuropathy and reduces nerve conduction and vibration threshold abnormalities in type 1 diabetes mellitus. In type 2 diabetes mellitus, enhanced glucose control reduces the incidence of clinical neuropathy, although this was not formally statistically significant (P = 0.06). However, enhanced glucose control does significantly reduce nerve conduction and vibration threshold abnormalities. Importantly, enhanced glucose control significantly increases the risk of severe hypoglycemic episodes, which needs to be taken into account when evaluating its risk/benefit ratio.

Diabetic neuropathy: clinical manifestations and current treatments

Diabetic peripheral neuropathy is a prevalent, disabling disorder. The most common manifestation is distal symmetrical polyneuropathy (DSP), but many patterns of nerve injury can occur. Currently, the only effective treatments are glucose control and pain management. While glucose control substantially decreases the development of neuropathy in those with type 1 diabetes, the effect is probably much smaller in those with type 2 diabetes. Evidence supports the use of specific anticonvulsants and antidepressants for pain management in patients with diabetic peripheral neuropathy. However, the lack of disease-modifying therapies for diabetic DSP makes the identification of new modifiable risk factors essential. Growing evidence supports an association between components of the metabolic syndrome, including prediabetes, and neuropathy. Studies are needed to further explore this association, which has implications for the development of new treatments for this common disorder.

Trends in the prescription of antidiabetic medications in France: evidence from primary care physicians

This study examined prescribing patterns for antidiabetic medications in France and explored the relationships between those patterns and changes in patient characteristics. Data were obtained from the IMS Disease Analyzer-Mediplus France Database (IMS Health Incorporated, London, United Kingdom). Patients were included in the study if they were identified as having type 2 diabetes during the calendar years 2001 to 2003. Univariate analyses examined changes in patient characteristics and trends in prescribing over time. In addition, multivariate logistic regression analysis examined the impact of the year on the likelihood of a patient's receiving prescriptions for a specific therapy. A total of 14,281 unique diabetic patients were studied during the years 2001 through 2003. An average of 1.28 drug therapy episodes per calendar year was reported among individual users of antidiabetic agents. Univariate analysis revealed that between 2001 and 2003, monotherapy with sulfonylurea decreased from 34.98% to 29.47% (P<.0001), monotherapy with metformin increased from 17.38% to 21.31% (P<.0001), and monotherapy with insulin increased from 1.71% to 2.27% of the population (P=.0437). Multivariate logistic regression analyses that compared prescription therapy episodes in 2003 with those in 2001 revealed that the influence of the year on the likelihood of metformin or insulin use (alone or in combination with other medications) was positive and significant (P<.05). In contrast, the influence of the year on the likelihood of sulfonylurea monotherapy use was negative and significant (P<.05). In France, antidiabetic medication prescribing patterns changed from 2001 to 2003. In general, the trend has been away from sulfonylurea monotherapy and toward metformin monotherapy, insulin monotherapy, or combination therapy.

Symmetry of nerve conduction studies in different stages of diabetic polyneuropathy

Nerve conduction studies (NCS) in diabetic sensorimotor polyneuropathy (DSP) are sensitive, noninvasive, and associated with small coefficients of variation, and correlate well with underlying peripheral nerve morphological change. For these reasons, the current reference standard for DSP involves multivariate instruments that emphasize NCS results. However, the interside symmetry of NCS findings in different stages of DSP are unknown, although requirement for symmetry has been suggested in clinical trials of DSP. We therefore aimed to determine the degree of symmetry of NCS findings in DSP of differing severity stages. A cohort of diabetic patients, including patients without neuropathy and those with mild to severe DSP, was studied. We also studied a series of nondiabetic, healthy subjects. A variation of stratified sampling by means of a clinical neuropathy score ensured that a broad spectrum of neuropathy was studied. A total of 478 subjects was ascertained; patient accrual was discontinued when the smallest clinical group consisted of 50 subjects. Nerve conduction studies were conducted prospectively and in a blinded fashion using surface recordings, averaging for sensory action potentials, control of limb temperature, and standardized techniques. Median and ulnar motor and sensory, peroneal and tibial motor, and sural NCS were performed. Interside symmetry, independent of neuropathy severity, was observed for all investigated nerves, except for the median sensory nerve action potential amplitude, which was lower on the right side. These results confirm that abnormal NCS findings consistent with DSP are reliably symmetrical with the exception of the amplitude of the median sensory nerve action potential. Thus, unilateral evaluation of NCS in DSP is sufficient as a reference standard in clinical trials. We also conclude that great degrees of asymmetry in NCS results are reason to question inclusion of DSP patients in clinical trials.

Status of current clinical trials in diabetic polyneuropathy

Peripheral polyneuropathy is the most frequent complication of diabetic mellitus. In spite of many clinical trials of different specific interventions for diabetic polyneuropathy, intensive glycemic control remains the only effective specific therapy currently available for this troublesome complication. This systematic overview reports the status of current clinical trials in diabetic polyneuropathy with an emphasis on those interventions directed towards specific pathophysiological derangements. A discussion of clinical trials of agents directed towards relieving painful symptoms of diabetic polyneuropathy concludes this overview.

The quality of life of elderly diabetic patients

The objective of this study was to evaluate the health-related quality of life (HRQoL) of elderly diabetic patients. A cross-sectional, questionnaire survey of diabetic subjects aged 65-84 years (n=177 respondents) from three community health centers in Stockholm County. The HRQoL was assessed by the Swedish Health-Related Quality of Life Survey (SWED-QUAL), a generic HRQoL questionnaire adapted from the Medical Outcomes Study (MOS) and consisting of 67 items covering broad aspects of the HRQoL. Diabetic subjects were compared with age- and gender-matched controls from a random standard population sample (SPS) of the Swedish population. Medical data on the diabetic subjects were extracted from medical records. The HRQoL, as regarded 7 of the 13 scales, was poorer in diabetic subjects than in the SPS controls. These scales were "general health perceptions," "physical functioning," "satisfaction with physical health," "role limitations due to physical health," "pain," "sleep problems," and "role limitations due to emotional health." Atheromatous complications and nonvascular disease were significant predictors of a poor HRQoL. "Cognitive functioning" was the only HRQoL scale on which diabetic subjects with high levels of HbA(1c) (HbA(1c)>7.0%) scored worse than those with acceptable levels (HbA(1c)<7.0%). In our study, elderly diabetic subjects had a poorer HRQoL than the general population, especially regarding physical health. Poor metabolic control was associated with reduced cognitive function.