Autonomic neuropathy in non-insulin dependent (type II) diabetes mellitus. Possible influence of obesity

Impact of glycemic control over cardiac autonomic neuropathy

Purpose

Cardiovascular autonomic neuropathy (CAN) is one of the most common and serious complications associated with diabetes and is defined as the impairment of the autonomic control of the cardiovascular system, whose prevalence in Indian population has been reported to be > 50%. The risk factors associated with CAN include hyperglycemia, duration of diabetes, hypertension, dyslipidemia, and obesity. This study was conducted to examine the association of CAN with its determinants among diabetics.

Methods

Socio-demographic characteristics were noted alongwith performance of biochemical analyses of blood samples according to standard hospital pathology laboratory protocols. Clinical assessment of CAN comprised a of 5 indexes, including 3 heart rate variability parameters (resting tachycardia, Qtc interval > 440 msec, exercise intolerance) and 2 blood pressure parameters (orthostatic hypotension, abnormal hand gripping test).

Results

The odds of CAN increased with poor glycemic control (FBS ≥ 126 mg/dL (OR = 1.17 (1.02-10.68); 2 hr PPBS ≥ 200 mg/dL (OR 1.63 (1.26-8.82) and HbA1c ≥ 6.5% (OR = 10.68 (1.54-208.02). Significant difference was also found in relation to duration of diabetes, weight and body mass index of the participants with various grades of CAN.

Conclusions

CAN is associated strongly with poor glycemic control. Obesity seems to be involved in the impairments of the cardiac autonomic function and this factor must therefore be taken into account in future studies when interpreting the results. Body mass control and glycemic control could provide an important approach to reducing CAN.

Physical activity and dietary interventions in diabetic neuropathy: a systematic review

PURPOSE

Diabetic neuropathy is a common and disabling disorder, and there are currently no proven effective disease-modifying treatments. Physical activity and dietary interventions in patients with diabetes and diabetic neuropathy have multiple beneficial effects and are generally low risk, which makes lifestyle interventions an attractive treatment option. We reviewed the literature on the effects of physical activity and dietary interventions on length-dependent peripheral neuropathy and cardiac autonomic neuropathy in diabetes.

METHODS

The electronic database PubMed was systematically searched for original human and mouse model studies examining the effect of either dietary or physical activity interventions in subjects with diabetes, prediabetes, or metabolic syndrome.

RESULTS

Twenty studies are included in this review. Fourteen studies were human studies and six were in mice. Studies were generally small with few controlled trials, and there are no widely agreed upon outcome measures.

CONCLUSIONS

Recent research indicates that dietary interventions are effective in modifying diabetic neuropathy in animal models, and there are promising data that they may also ameliorate diabetic neuropathy in humans. It has been known for some time that lifestyle interventions can prevent the development of diabetic neuropathy in type 2 diabetes mellitus subjects. However, there is emerging evidence that lifestyle interventions are effective in individuals with established diabetic neuropathy. In addition to the observed clinical value of lifestyle interventions, there is emerging evidence of effects on biochemical pathways that improve muscle function and affect other organ systems, including the peripheral nerve. However, data from randomized controlled trials are needed.

Autonomic Neuropathy-a Prospective Cohort Study of Symptoms and E/I Ratio in Normal Glucose Tolerance, Impaired Glucose Tolerance, and Type 2 Diabetes

Background

Autonomic neuropathy in diabetes, in addition to causing a range of symptoms originating from the autonomic nervous system, may increase cardiovascular morbidity. Our aim was to study the progression of autonomic neuropathy, based on symptom score and evaluation of an autonomic test, in persons with normal and impaired glucose tolerance and in patients with type 2 diabetes (T2D).

Methods

Participants were recruited in 2003/2004 with a follow-up in 2014. The participants’ glucose tolerance was categorized using oral glucose tolerance tests. Symptoms were evaluated using an autonomic symptom score (ASS), ECG was used to test cardiac autonomic function based on the expiration/inspiration ratio (E/I ratio), and blood samples were taken on both occasions.

Results

ASSs were higher at follow-up in the T2D patients than in the normal glucose tolerance group (mean 1.21 ± 1.30 vs. 0.79 ± 0.7; p < 0.05). E/I ratio did not deteriorate more than could be expected as an aging effect in well-controlled T2D. No relationship was found between E/I ratio and HbA1c or ASS.

Conclusion

The presence of autonomic symptoms increased over time in T2D patients, but the symptoms did not correlate with the E/I ratio in this metabolically well-controlled cohort. ASSs can be a useful clinical tool when assessing the progression of autonomic dysfunction in patients with abnormal glucose metabolism.

Moderate intensity exercise improves heart rate variability in obese adults with type 2 diabetes

AIM

The aim of this study was to determine the effect of moderate aerobic exercise on heart rate variability (HRV) in obese adults with type 2 diabetes.

METHODS

Forty-one obese adults with type 2 diabetes participated in this study. Anthropometric and metabolic parameters were measured, and resting electrocardiogram (ECG) for the HRV analysis at spontaneous respiration was recorded for 5 min in supine position before and after six months of supervised aerobic training given thrice-a-week.

RESULTS

The mean age, body mass index (BMI), and duration of diabetes of the study population were 44.1 ± 4.5 years, 30.94 ± 1.36 kg/m2, and 16.3 ± 2.7 years, respectively. In time domain variables, standard deviation of all RR intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD) and percentage of consecutive RR intervals that differ by more than 50 ms (pNN50) were significantly increased after exercise. In frequency domain variables, high frequency (HF) (ms2) and HF (nu) were significantly increased while low frequency (LF) (ms2) and LF/HF ratio were significantly decreased after exercise. But LF (nu) was unaffected after exercise.

CONCLUSION

This study suggests that thrice-a-week moderate intensity aerobic exercise for six months improves cardiac rhythm regulation as measured by HRV in obese adults with type 2 diabetes.

The impact of telephonic wellness coaching on weight loss: A "Natural Experiments for Translation in Diabetes (NEXT-D)" study

OBJECTIVE

To evaluate the impact of a population-based telephonic wellness coaching program on weight loss.

METHODS

Individual-level segmented regression analysis of interrupted time series data comparing the BMI trajectories in the 12 months before versus the 12 months after initiating coaching among a cohort of Kaiser Permanente Northern California members (n = 954) participating in The Permanente Medical Group Wellness Coaching program in 2011. The control group was a 20:1 propensity-score matched control group (n = 19,080) matched with coaching participants based on baseline demographic and clinical characteristics.

RESULTS

Wellness coaching participants had a significant upward trend in BMI in the 12 months before their first wellness coaching session and a significant downward trend in BMI in the 12 months after their first session equivalent to a clinically significant reduction of greater than one unit of baseline BMI (P < 0.01 for both). The control group did not have statistically significant decreases in BMI during the post-period.

CONCLUSIONS

Wellness coaching has a positive impact on BMI reduction that is both statistically and clinically significant. Future research and quality improvement efforts should focus on disseminating wellness coaching for weight loss in patients with diabetes and those at risk for developing the disease.

Prevalence of Cardiovascular Autonomic Neuropathy in a Cohort of Patients With Newly Diagnosed Type 2 Diabetes: The Verona Newly Diagnosed Type 2 Diabetes Study (VNDS)

OBJECTIVE

Cardiovascular autonomic diabetic neuropathy (CAN) is a serious complication of diabetes. No reliable data on the prevalence of CAN among patients with newly diagnosed type 2 diabetes are available. Therefore, the aim of this study was to estimate the prevalence of CAN among patients with newly diagnosed type 2 diabetes.

RESEARCH DESIGN AND METHODS

A cohort of 557 patients with newly diagnosed type 2 diabetes with cardiovascular autonomic test results available was selected. Early and confirmed neuropathy were assessed using a standardized methodology and their prevalences determined. A multivariate logistic regression analysis was modeled to study the factors associated with CAN.

RESULTS

In the entire cohort, the prevalence of confirmed CAN was 1.8%, whereas that of early CAN was 15.3%. Prevalence did not differ between men and women. In the multivariate analyses BMI results were independently and significantly associated with CAN after adjusting for age, sex, hemoglobin A1c, pulse pressure, triglyceride-to-HDL cholesterol ratio, kidney function parameters, and antihypertensive treatment.

CONCLUSIONS

CAN could be detected very early in type 2 diabetes. This study may suggest the importance of performing standardized cardiovascular autonomic tests after diagnosis of type 2 diabetes.

Cardiovascular autonomic neuropathy in context of other complications of type 2 diabetes mellitus

The aim of this study was to investigate the relationship between cardiac autonomic neuropathy (CAN) and other micro- and macrovascular complications and risk factors for type 2 diabetes. We included, in this study, 149 patients with type 2 diabetes. We evaluated their cardiovascular risk factors, demographic data, and any major micro- and macrovascular complications of their diabetes. Assessments of CAN were based upon Ewing's battery.

RESULTS

CAN was present in 38.9% of patients. In the CAN group, the duration of diabetes, BMI, systolic blood pressure, lipid levels, and HBA1c were all significantly higher than those in the other group. A significant association was found between CAN and retinopathy, peripheral neuropathy, ABI, and IMT. Multivariate logistic regression demonstrated that, in type 2 diabetes, the odds of CAN (OR (95% confidence intervals)) increase with the age of the patients (1.68 (1,4129-2.0025)), the average diabetes duration (0.57 (0.47-0.67)), cholesterol (1.009 (1.00-1.01)), HbA1c levels (1.88 (1.31-2.72)), peripheral neuropathy (15.47 (5.16-46.38)), BMI (1.12 (1.05-1.21)), and smoking (2.21 (1.08-4.53)).

CONCLUSIONS

This study shows that CAN in type 2 diabetes is significantly associated with other macro- and microvascular complications and that there are important modifiable risk factors for its development.

Cardiovascular autonomic function and vibration perception threshold in type 2 diabetes mellitus

OBJECTIVE

The aim of this study was to compare cardiovascular autonomic function tests (AFT) and vibration perception threshold (VPT) of patients with type 2 diabetes mellitus (T2DM) with controls.

RESEARCH DESIGN/METHODS

The study was conducted on 60 diabetic patients comparing with 30 controls. The cardiovascular AFT and VPT were assessed in both groups.

RESULTS

Among cardiovascular AFT, E:I ratio [1.24 (1.2-1.32) vs 1.3 (1.24-1.4), p=0.001], and Valsalva ratio [1.28 (1.22-1.4) vs 1.6 (1.5-1.73), p=0.001], the indicators of parasympathetic reactivity were reduced in T2DM. Rise in DBP during handgrip, an indicator of sympathetic reactivity was lower in T2DM [12 (10-14) vs 16 (14-18) mmHg, p=0.001] whereas, fall in SBP during head up tilt [4 (4-8) vs 5 (4-8) mmHg] was comparable. VPT (somatic sensation) was comparable between T2DM and control.

CONCLUSION

Autonomic involvement is more marked than somatic, and parasympathetic involvement is more marked than the sympathetic, possibly reflecting severity and chronological pattern of their involvement.

Special considerations on the management of Latino patients with type 2 diabetes mellitus

BACKGROUND

Latinos are the largest minority population in the United States, and are characterized by higher rates of obesity and diabetes compared to Whites. The prevalence of diagnosed diabetes in Latinos is two-fold higher than in Caucasians, and Latinos suffer from higher rates of diabetic complications and mortality. As the diabetes epidemic continues to expand and exert greater socioeconomic strain on national healthcare systems, the success of global and national healthcare initiatives for diabetes prevention and improvement of care will depend upon strategies targeted specifically toward this population. Essential to such strategies is an understanding of success factors unique to the Latino population for diabetes prevention and achievement of optimal treatment outcomes.

METHODS

A PubMed search was conducted for literature describing type 2 diabetes and its complications in Latinos. Specifically, we sought data describing epidemiology, disparities, management considerations, and success factors in this population.

RESULTS

The title search yielded more than 2000 articles, 80 of which were deemed directly relevant to this review. The inherent limitations of this subjective selection process are acknowledged.

CONCLUSIONS

A number of studies have highlighted various ethnic disparities in Latinos with diabetes including higher HbA1c levels, greater rates of obesity and metabolic syndrome, and a larger proportion of individuals with inadequate access to care. While relatively fewer studies describe success factors for redressing cultural disparities in diabetes, the current body of literature supports primary care strategies aimed at effective provider-patient relationships and culturally tailored education and lifestyle modification regimens. Further research demonstrating effective, culturally tailored practices that are suitable to the primary care setting would be of value to providers treating Latinos with diabetes.

Sympathetic nerve dysfunction is common in patients with chronic intestinal pseudo-obstruction

GOAL

To clarify whether disturbances in the autonomic nervous system, reflected in abnormal cardiovascular reflexes, could explain symptoms of impaired heat regulation in patients with intestinal pseudo-obstruction.

BACKGROUND

Chronic intestinal pseudo-obstruction is a clinical syndrome characterized by diffuse, unspecific gastrointestinal symptoms due to damage to the enteric nervous system or the smooth muscle cells. These patients often complain of excessive sweating or feeling cold, suggesting disturbances in the autonomic nervous system. Earlier studies have pointed to a coexistence of autonomic disturbances in the enteric and cardiovascular nervous system.

STUDY

Thirteen consecutive patients (age range 23 to 79, mean 44 y) fulfilling the criteria for chronic intestinal pseudo-obstruction were investigated. Six of them complained of sweating or a feeling of cold. Examination of autonomic reflexes included heart rate variation to deep-breathing (expiration/inspiration index), heart rate reaction to tilt (acceleration index, brake index), and vasoconstriction (VAC) due to indirect cooling by laser doppler (VAC-index; high index indicates impaired VAC). Test results in patients were compared with healthy individuals.

RESULTS

Patients had significantly higher (more abnormal) median VAC-index compared with healthy controls [1.79 (interquartile ranges 1.89) vs. 0.08 (interquartile ranges 1.29); P=0.0007]. However, symptoms of impaired heat regulation were not related to the VAC-index. There were no differences in expiration/inspiration, acceleration index, or brake index between patients and controls.

CONCLUSIONS

The patients with severe gastrointestinal dysmotility showed impaired sympathetic nerve function which, however, did not seem to be associated with symptoms of impaired heat regulation.

Could we predict asymptomatic cardiovascular autonomic neuropathy in type 1 diabetic patients attending out-patients clinics?

BACKGROUND AND AIMS

Diabetic cardiovascular autonomic neuropathy (CAN) is associated with increased morbidity and mortality. This complication may be asymptomatic for a long time. The aim of this study was to assess the prevalence, severity and predictors of asymptomatic CAN in patients with type 1 diabetes mellitus (DM1).

PATIENTS AND METHODS

107 patients with DM1 were enrolled: 52 men and 55 women aged 39.8 +/- 12.4 years (18-72), duration of DM 16.6 +/- 9.5 years (0.5-43), age at DM manifestation 23.5 +/- 12.8 years (1-54) and BMI 25.1 +/- 3.2 (18.9-33.91). CAN was assessed using standard cardiovascular reflex tests (Ewing battery) and the patients were divided into three groups according to the results: Group 0, without CAN; Group I, 1(st) degree CAN; Group II, 2(nd) degree CAN. We assessed the most frequent relationships between CAN and chronic complications, episodes of severe hypoglycemia, time-related parameters (age of patients, duration of diabetes, age at manifestation), glycosylated hemoglobin (HbA(1)c), BMI, cardiovascular diseases and blood pressure, and determined the predictability of CAN on the basis of these relationships.

RESULTS

Only 50 of the 107 patients (46%) showed no CAN. We found 1(st) degree CAN in 38 patients (36%) and 2(nd) degree CAN in 19 (18%). CAN correlated more significantly with the duration of diabetes (p < 0.001) than with age (p < 0.05). The relationship between CAN and HbA(1)c was on the borderline of statistical significance (p = 0.053). We found a positive correlation between CAN and the presence of chronic complications [peripheral neuropathy (p < 0.001), retinopathy (p < 0.001), and some markers of nephropathy: creatinine (p < 0.03), albuminuria (p < 0.01)]. Although blood pressure was within the physiological range (124.2/74.5 +/- 11.5/7.8 mmHg) in all patients, a positive correlation with CAN was confirmed (p < 0.05). No relationship with occurrence of severe hypoglycemia was found.

CONCLUSIONS

According to our results, asymptomatic CAN is very frequent in patients with DM1. By using multifactorial logistic regression (step-wise) analysis we demonstrated that if albuminuria, peripheral neuropathy and elevated systolic BP are present simultaneously, there is a high probability that the patient also has CAN (84.9% of initial group correctly predicted, p < 0.001).

Subclinical sympathetic neuropathy appears early in the course of Crohn's disease

BACKGROUND

We have previously demonstrated that patients with Crohn's disease (CD) of long duration have signs of autonomic neuropathy. The aim of this study was to examine whether autonomic neuropathy is an early manifestation of CD, or a sign appearing late in the course.

METHODS

Twenty patients, median age 40 years, with a short duration of CD were included. Examination of autonomic reflexes included heart rate reaction to tilt (acceleration index - AI, brake index - BI) and heart rate variation to deep-breathing (expiration/inspiration index-E/I). Seven years later the same examinations were repeated, and in addition we examined the vasoconstriction response to indirect cooling by laser Doppler (vasoconstriction-index - VAC-index). The results were compared with healthy individuals.

RESULTS

There was no difference in the blood pressure between controls and the patients with CD at rest, but eight minutes after tilt, the systolic blood pressure was lowered in patients compared to controls, both at the first assessment (p = 0.016) and after seven years (p = 0.042). The change in systolic blood pressure between rest and eight minutes after tilt was not significant at the first assessment, while a significant change compared to controls was observed seven years later (p = 0.028). This indicates a progressive dysfunction. There were no differences in E/I, AI, BI or VAC indexes between patients and controls.

CONCLUSION

Patients with CD suffer from autonomic neuropathy early in their disease, suggesting involvement of many different organ systems in this entity.

Enteric ganglioneuritis and abnormal interstitial cells of Cajal: features of inflammatory bowel disease

BACKGROUND

An increased prevalence of irritable bowel syndrome (IBS) and disturbances in cardiac and blood pressure reflexes have been described in patients with Crohn's disease (CD) and ulcerative colitis (UC). These features could be due to abnormalities in the gastrointestinal neurotransmission. The aims of this study were to examine whether histopathologic changes in the enteric nervous system correlate with disturbances in cardiac and blood pressure reflexes and the occurrence of IBS- and dyspepsia-like symptoms in these patients.

METHODS

Thirty patients with CD and UC with bowel resection were examined by deep-breathing and orthostatic tests. The resection specimens were evaluated histologically regarding visceral neuro- or myopathy. All medical records were studied for treatment and clinical course.

RESULTS

Ganglioneuritis was observed in 11 of 19 patients with CD and in 5 of 11 with UC. Only patients with CD had ganglioneuritis in the small intestine. Moreover, in CD the interstitial cells of Cajal (ICCs) in the small bowel showed atrophy and vacuolar degeneration, along with a reduced number of cells (P = 0.005). In UC the colonic ICCs were hyperplastic (P = 0.05) without signs of degeneration. The indices of deep-breathing and orthostatic tests were impaired, except in CD with ganglioneuritis, who showed normal test values. There were no correlations between histopathologic alterations versus IBS and dyspepsia.

CONCLUSIONS

Visceral ganglioneuritis and pathologic ICCs were observed in patients with CD and UC. However, these histopathologic abnormalities could not be related to the clinical or autonomic features of the disease.

Impact of surgically induced weight loss on cardiovascular autonomic function: one-year follow-up

OBJECTIVE

To determine the impact of surgically induced weight loss on cardiovascular autonomic function in subjects with severe obesity and examine whether the effect was comparable for persons with and without diabetes.

RESEARCH METHODS AND PROCEDURES

Twenty-six severely obese individuals (BMI = 48 +/- 7 kg/m(2)) underwent bariatric surgery (laparoscopic Roux-en-Y gastric bypass, n = 21; laparoscopic adjustable gastric banding, n = 5). Cardiovascular autonomic function (heart rate variation during deep breathing and the Valsalva maneuver) was assessed before and 6 and 12 months after surgery.

RESULTS

Twelve months after bariatric surgery, there was a 28% decrease in BMI. There was an increase in all parasympathetic indices of autonomic function (all assessment modalities, p < 0.05) with weight loss. The amount of improvement from baseline for all measures of autonomic function did not differ for those with or without diabetes.

DISCUSSION

Surgically induced weight loss 12 months after surgery has a favorable effect on cardiovascular autonomic function in severely obese individuals with and without diabetes.

Right-left correlation of the sympathetically induced fluctuations of photoplethysmographic signal in diabetic and non-diabetic subjects

Photoplethysmography (PPG) records the cardiac-induced changes in tissue blood volume by light-transmission measurements. The baseline and amplitude of the PPG signal show very low-frequency (VLF) spontaneous fluctuations, which are mediated by the sympathetic nervous system, and high correlation between right and left extremities of healthy subjects. As sympathetic neuropathy is one of the diabetic complications, the right-left correlation of the PPG fluctuations was examined in diabetic patients. The PPG signal was simultaneously measured in the two index fingers and the two second toes of 35 diabetic patients and 33 non-diabetic subjects. For each PPG pulse, the baseline and amplitude were determined, and the right-left correlation coefficients of the VLF fluctuations in the baseline and amplitude were derived. The VLF fluctuations in the baseline showed high right-left correlation, both for fingers (0.93 +/- 0.05) and toes (0.93 +/- 0.06), for the non-diabetic subjects, and significantly lower correlation (0.78 +/- 0.22 and 0.84 +/- 0.17, respectively) for the diabetic patients. Similar results were obtained for the amplitude VLF fluctuations. The right-left correlation coefficients for diabetic patients decreased with the disease duration for the toe baseline and toe amplitude fluctuations and correlated with heart rate response to deep breathing for the finger baseline and toe amplitude fluctuations. The right-left correlation coefficients of the PPG fluctuations provide a simple and convenient means for assessing the adequacy of the sympathetic nervous system function.

Early parasympathetic neuropathy associated with elevated fasting plasma C-peptide concentrations and late parasympathetic neuropathy with hyperglycaemia and other microvascular complications

AIMS

To examine the relationship between parasympathetic neuropathy, hyperinsulinaemia, glycaemic control (HbA(1c)), and future diabetic complications.

METHODS

We assessed parasympathetic nerve function [expiration/inspiration (E/I) ratio], glomerular filtration rate (GFR), glycaemic control (HbA(1c)), fasting plasma (f-p-) C-peptide in 82 Type 2 diabetic patients (age 61 +/- 1 years) 5 and 12-15 years after diagnosis. Diabetic retinopathy was assessed 15 years after diagnosis.

RESULTS

High HbA(1c) values in the first study were associated with retinopathy (with 8.6 +/- 2.0 vs. without retinopathy 6.2 +/- 1.9%; P < 0.0001) and disturbed parasympathetic nerve function (low E/I ratio; r(s) = -0.41; P = 0.0061) in the second study, as well as with deteriorations in GFR between the first and second study (r(s) = 0.62; P < 0.0001). Patients with parasympathetic neuropathy in the first study had significantly higher f-p-C-peptide concentrations than those without 3 years (1.20 +/- 0.43 vs. 0.86 +/- 0.40 nmol/l; P = 0.0015) and 5 years (1.20 +/- 0.44 vs. 0.82 +/- 0.33 nmol/l; P < 0.0001), but not 15 years after diagnosis.

CONCLUSION

High HbA(1c) values 5 years after diagnosis of Type 2 diabetes were associated with retinopathy, disturbed parasympathetic nerve function, and deterioration in GFR 7-10 years later. Parasympathetic neuropathy 5 years after diagnosis was associated with high C-peptide concentrations. Parasympathetic nerve function has to be considered when beta-cell function is evaluated. Hyperglycaemia is an important factor for the development of complications in Type 2 diabetes.

Serum cystatin C advantageous compared with serum creatinine in the detection of mild but not severe diabetic nephropathy

OBJECTIVE

To determine whether serum cystatin C is more accurate than serum creatinine in the detection of diabetic nephropathy, also after adjustment for age.

METHODS

Forty-one patients with type 1 and 82 patients with type 2 diabetes were evaluated with serum creatinine, serum cystatin C, and (51)Cr-EDTA clearance (reference method). Cystatin C was measured by a particle-enhanced turbidimetric method and creatinine by an enzymatic method. Statistical estimations were performed both without and with age adjustment created by z-scores for (51)Cr-EDTA clearance, creatinine, and cystatin C. The cut-off levels for glomerular filtration rate (GFR) ((51)Cr-EDTA clearance) were 60 and 80 mL min(-1) 1.73 m(-2), respectively, in absolute values and 80, 90 and 95% CIs, respectively, in age-adjusted values (z-scores).

RESULTS

Estimations without age adjustment showed significantly (P = 0.0132) closer correlation for cystatin C (r = 0.817) versus (51)Cr-EDTA clearance as compared with creatinine (r = 0.678). However, when using age-adjusted values, the correlation for cystatin C and creatinine, respectively, versus (51)Cr-EDTA clearance did not differ. When comparing the diagnostic utilities for serum cystatin C versus serum creatinine in manifest renal impairment (GFR < 60 mL min(-1) 1.73 m(-2) or z-scores <-1.28 SD), there were no significant differences between the two markers whether age adjusted or not. However, for diagnosing mild nephropathy (GFR < 80 mL min(-1) 1.73 m(-2) or z-score -0.84 SD), serum cystatin C is significantly more useful.

CONCLUSIONS

Serum cystatin C performed better compared with serum creatinine even when measured enzymatically, to detect mild diabetic nephropathy. However, serum creatinine was as efficient as serum cystatin C to detect advanced diabetic nephropathy.

Sympathetic and parasympathetic neuropathy are frequent in both type 1 and type 2 diabetic patients

OBJECTIVE

The aim of this study was to evaluate the frequency of sympathetic versus parasympathetic neuropathy among type 1 and type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

There were 43 patients with type 1 and 17 with type 2 diabetes who were investigated. Sympathetic nerve function was assessed by measurement of the vasoconstriction (VAC) index by laser Doppler perfusion imaging of a locally heated finger followed by indirect cooling. Parasympathetic nerve function was assessed by R-R interval variation during deep breathing as measured by the expiration/inspiration (E/I) ratio. Results were expressed as age-corrected z scores in SD; VAC index >1.64 SD and E/I ratio <-1.64 SD were considered abnormal.

RESULTS

VAC index was abnormal in 40% with type 1 and 41% with type 2 diabetes, whereas the E/I ratio was abnormal in 42% with type 1 and 65% with type 2 diabetes. There was a clear association between VAC index and E/I ratio among type 1 (rs=0.525; P=0.0002) but not among type 2 (rs=0.10) diabetic patients. Among type 2 diabetic patients, the degree of dysfunction was most severe regarding parasympathetic function (P=0.0167).

CONCLUSIONS

Sympathetic and parasympathetic neuropathy were frequent in both type 1 and type 2 diabetic patients. However, there was a difference between the two types of diabetes. Sympathetic and parasympathetic nerve functions correlated in type 1 but not in type 2 diabetic patients. The explanation for this discrepancy might be that parasympathetic nerve function was most severely affected among type 2 diabetic patients.

Cardiac autonomic neuropathy in diabetic patients: influence of diabetes duration, obesity, and microangiopathic complications--the French multicenter study

The current study sought to examine in a large series of diabetic patients the prevalence of symptoms of autonomic neuropathy and subclinical cardiac autonomic neuropathy (CAN) and their determinants, particularly the influence of diabetes duration, obesity, and microangiopathic complications. Three hundred ninety-six patients, 245 type 1 and 151 type 2, were recruited in 7 French departments of diabetology. CAN was detected by measuring heart rate variability during 3 standardized tests: deep-breathing, Valsalva, and lying-to-standing tests. At least 24.5% of the patients had one or more symptoms suggesting overt autonomic neuropathy. They were older than those free of dysautonomic symptom (P<.001). The deep-breathing test correlated negatively with body mass index (BMI) in type 2 diabetic patients (P<.0001). In the whole population, the deep-breathing and Valsalva tests correlated negatively with diabetes duration (P=.0004 and.019, respectively) and the log urinary albumin/creatinine ratio (P<.002 and.001, respectively). The prevalence of CAN (51%) was higher than the prevalence of other diabetic complications. The rate of moderate and severe CAN (defined by 2 or 3 abnormal CAN function tests) was higher in type 1 than in type 2 diabetic patients (P=.031). It correlated with diabetes duration (P=.026) and was higher in the patients with retinopathy than in those without (P=.035). Among type 2 diabetic patients, the prevalence of CAN was higher in the obese ones (P=.033); in a logistic regression taking age, diabetes duration, and obesity as independent variables, CAN was associated independently with obesity (P=.034). Mild or moderate CAN was found in 33.8% and 13.0% of the 80 patients with diabetes duration less than 18 months. We conclude that CAN is found early in the course of diabetes and should be considered as a prognostic marker of microangiopathic complications. Obesity could be involved in the impairment of CAN function in type 2 diabetics and body weight control could provide an approach to reducing neuropathic complications.

Diagnosis and management of diabetic autonomic neuropathy

Autonomic neuropathy affects every system in the body including the eye, cardiovascular, respiratory, and gastrointestinal and neurovascular systems. The diagnosis confers an attenuated life expectancy, but much can be done to alleviate symptoms and to address the underlying disorder.

Obesity is not a confounding factor for performing autonomic function tests in individuals with diabetes mellitus

AIM

Cardiovascular autonomic neuropathy is a serious complication of diabetes mellitus. Previous studies have revealed conflicting results with regard to the role of obesity and its effect on the performance of tests (e.g. RR-variation during deep breathing) for the determination of the presence of cardiovascular autonomic dysfunction. The objective of this study was to determine if obesity affects the performance and the reproducibility of autonomic function tests.

METHODS

This cross-sectional study included 159 diabetic individuals. Autonomic function tests included: RR-variation during deep breathing and the Valsalva ratio. These tests were assessed using the ANS2000 ECG Monitor and Respiration Pacer. RR-variation was measured by vector analysis (i.e. mean circular resultant, MCR). Reproducibility of the autonomic function tests was assessed by determining the coefficient of variation (CV) on repeat testing.

RESULTS

Using cut-off points to describe normal weight (body mass index (b.m.i.) < or = 25 kg/m(2)), overweight (b.m.i. 25.01-30 kg/m(2)), obese (b.m.i. 30.01-40 kg/m(2)), and morbidly obese (b.m.i. > or = 40.1 kg/m(2)), no difference was found for the MCR, Valsalva ratio, CV of the MCR, or CV of the Valsalva ratio among the various weight levels for individuals with type 1 or type 2 diabetes.

CONCLUSIONS

The results of this study indicate that obesity is not a confounding factor in the performance of autonomic function tests. Likewise, the reproducibility of autonomic function testing is not affected by obesity. Assessment of autonomic function is important for obese and non-obese individuals given that reduced RR-variation is associated with exercise intolerance, intraoperative cardiovascular lability and increased risk of mortality.

Delayed gastric emptying rate in Type 1 diabetics with cardiac autonomic neuropathy

Gastroparesis is a frequent complication of longstanding diabetes and has been attributed to vagal nerve dysfunction, occurring as part of a generalized autonomic neuropathy. We wanted to clarify the relationship between delayed gastric emptying (GE) and cardiac autonomic neuropathy (CAN) in type 1 diabetics. Using a standardized ultrasound technique, GE was studied in 20 type 1 diabetic patients with poor glycaemic control despite good compliance and 10 normal healthy volunteers (Group 1). Measurements of GE were done on condition that the fasting blood glucose was 3.5-9.0 mmol/l. Diabetic patients were classified into two groups according to the absence (Group 2) or presence (Group 3) of CAN, using the deep breathing test (E:I ratio) to evaluate parasympathetic vagal nerve function. Age-related reference values were used to evaluate the indices of CAN. The supine resting heart rate was also checked, and the patients were asked for symptoms of gastroparesis. The three groups were similar in terms of sex and smoking habits, and there was no significant difference regarding the age and body mass index (BMI). The mean duration of diabetes and the glycaemic control (HbA1c) was insignificant between patients in Groups 2 and 3. Diabetic patients in Group 3 showed lower gastric emptying rates (GER) than the healthy volunteers in Group 1 (median GER 16% vs. 63%, P<.01) and the patients in Group 2 (median GER 16% vs. 54%, P<.01). No significant difference in GER could be seen between patients in Group 2 and subjects in Group 1 (median GER 54% vs. 63%, P=.08). Assuming that GER<45% indicated a delayed GE, 8 of 10 patients in Group 3 had delayed GE compared to only 3 of 10 patients in Group 2. There were disagreements between symptoms of gastroparesis and delayed GE. We conclude that there is a significant lower GER in type 1 diabetic patients with CAN than in those without, unrelated to symptoms of gastroparesis.

Autonomic neuropathy in nondiabetic offspring of type 2 diabetic subjects is associated with urinary albumin excretion rate and 24-h ambulatory blood pressure: the Fredericia Study

The aim of this study was to examine the impact of parental type 2 diabetes on the autonomic nervous system and to determine whether autonomic neuropathy is present and associated with changes in 24-h ambulatory blood pressure (AMBP) and urinary albumin excretion rate (UAER) in nondiabetic subjects with parental type 2 diabetes. We examined 223 nondiabetic offspring of type 2 diabetic subjects and a control group of 258 offspring of nondiabetic subjects. The autonomic nervous system was assessed by three cardiovascular reflex tests, 24-h AMBP was measured with an oscillometric recorder (90207; Spacelabs, Redmond, WA), and UAER was determined through three overnight urine samples. The subjects with parental type 2 diabetes had significantly lower heart rate variation in all three bedside tests (P < 0.01) than subjects without parental diabetes. The prevalence of autonomic neuropathy in the nondiabetic offspring with parental type 2 diabetes (6.7%) was significantly (P < 0.01) higher compared with the control group (1.6%). Autonomic neuropathy was associated with a higher fasting insulin level (P < 0.05), higher UAER (P < 0.001), higher 24-h mean AMBP (P < 0.01), and reduced diurnal blood pressure variation (P < 0.001) after adjustment for age, sex, and BMI. In conclusion, parental type 2 diabetes was found to be associated with alterations in the autonomic nervous system in nondiabetic subjects. The presence of autonomic neuropathy in subjects with parental type 2 diabetes was associated with higher UAER, fasting insulin level, and 24-h AMBP and a reduced diurnal blood pressure variation. This study indicates that parental type 2 diabetes has an impact on the cardiac autonomic function in nondiabetic subjects.

Diabetes mellitus and Helicobacter pylori infection

Alterations of glucose metabolism in diabetes have been suggested as promoting Helicobacter pylori colonization. We performed a cross-sectional sero-prevalence study of diabetic patients (insulin-dependent, or type 1, and non-insulin-dependent, or type 2, diabetes mellitus) with H. pylori and compared them with a control group. Consecutive diabetic outpatients aged 12 to 75 y and with disease duration of greater than 1 y were enrolled. Helicobacter pylori status was evaluated by using an enzyme-linked immunosorbent assay for anti-H. pylori immunoglobulin G. Demographic data were obtained from each individual, and socioeconomic class was assessed by occupation and education level. A total of 891 individuals participated (240 with type-2 diabetes, 145 with type-1 diabetes, and 506 control subjects). After controlling for age, there was no significant difference in the prevalence of H. pylori infection in any age group. In fact, the prevalence of H. pylori was numerically higher among children in the control group than among children with type-1 diabetes (25% versus 9%, respectively; P = 0.1). Previous associations of H. pylori and diabetes may have arisen from failure to consider socioeconomic status or age. Because childhood is the most common period for acquisition of H. pylori infection, the higher prevalence of infection among the normal children as opposed to those with type-1 diabetes confirms the lack of an association.

Impact of body mass on autonomic function in persons with type 2 diabetes

The aim of this study was to investigate the influence of body mass on autonomic nerve function in persons with type 2 diabetes. Towards this aim we studied two groups of diabetic persons. Group 1: n = 30 lean (mean age 57.2+/-12.5 years, body mass index (BMI) 22.5+/-1.8 kg/m2]. Group 2: n = 35 overweight and obese (age 52.3+/-10.3 years, BMI 28.8 + 3.2 kg/m2). Autonomic neuropathy (DAN) was assessed using the battery of the five classical tests. DAN was diagnosed when at least two of the five tests were abnormal. Abnormalities of the heart rate based tests were considered as indication of parasympathetic and of blood pressure changes as indication of sympathetic dysfunction. The prevalence rates of DAN were not different between group 2 and group 1 (54.2 and 53.3%, respectively, P = 0.54). The same was valid for the rates of parasympathetic and sympathetic dysfunction in the studied groups (51.4 and 53.3% (P = 0.87) in group 2 and 34.2 and 33.3% (P = 0.93) in group 1, respectively). When the values of the arithmetic expression of each single autonomic function test were compared, no significant difference could be shown between the studied groups. In addition, no significant correlation was found between BMI and indices of DAN. These data indicate that moderate increase of body mass does not affect autonomic function in persons with type 2 diabetes.

Urinary albumin excretion rate is independently related to autonomic neuropathy in type 2 diabetes mellitus

OBJECTIVE

To evaluate if urinary albumin excretion rate (UAER) is independently related to subclinical autonomic neuropathy in type 2 diabetes.

DESIGN

A controlled cross-sectional study.

SETTING

Primary health care centre.

SUBJECTS

Consecutive recently diagnosed (< 1 year) type 2 diabetic patients (group A, n = 150) and patients with long-standing (median 11 years) type 2 diabetes (group B, n = 146) chosen at random. A nondiabetic control group (group C, n = 150) matched for age and gender to group A.

MAIN OUTCOME MEASURES

Neuropathy by cardiovascular reflex tests and UAER by nephelometry.

METHODS

Univariate statistics in group A + B (t-test chi 2- or McNemars test) with Valsalva and breathing ratios as categorical grouping variables and the independent variables gender, smoking, systolic and diastolic blood pressure, fasting serum cholesterol, HDL cholesterol, triglycerides, haemoglobin A1c, glucagon stimulated C-peptide, fasting and postload 1 and 2 h blood glucose and serum insulin, UAER, coronary heart disease and congestive heart failure. Logistic regression analyses in group A + B with Valsalva and breathing ratios as dependent categorical variables and age, systolic blood pressure, congestive heart failure, coronary heart disease, fasting blood glucose, serum triglycerides and UAER as independent variables.

RESULTS

Compared to nondiabetic subjects the diabetic patients of both groups were at increased risk of neuropathy as judged by the Valsalva ratio (P < 0.01). In known diabetic patients with a UAER > or = 30 mg 24-1 h neuropathy was more common than amongst their normoalbuminuric counterparts (Valsalva test P = 0.007, breathing test P = 0.02). In logistic regression analysis UAER independently explained abnormal Valsalva (P = 0.015) and breathing tests (P = 0.04) in the group A + B.

CONCLUSIONS

UAER is independently related to subclinical autonomic neuropathy in type 2 diabetes.

Early autonomic dysfunction in patients with diabetes mellitus assessed by spectral analysis of heart rate and blood pressure variability

Patients with diabetes mellitus (DM) often have alterations of the autonomic nervous system (ANS), even early in their disease course. Previous research has not evaluated whether these changes may have consequences on adaptation mechanisms in DM, e.g. to mental stress. We therefore evaluated whether patients with DM who already had early alterations of the ANS reacted with an abnormal regulatory pattern to mental stress. We used the spectral analysis technique, known to be valuable and reliable in the investigation of disturbances of the ANS. We investigated 34 patients with DM without clinical evidence of ANS dysfunction (e.g. orthostatic hypotension) and 44 normal control subjects (NC group). No patients on medication known to alter ANS responses were accepted. The investigation consisted of a resting state evaluation and a mental stress task (BonnDet). In basal values, only the 21 patients with type 2 DM were different in respect to body mass index and systolic blood pressure. In the study parameters we found significantly lower values in resting and mental stress spectral power of mid-frequency band (known to represent predominantly sympathetic influences) and of high-frequency and respiration bands (known to represent parasympathetic influences) in patients with DM (types 1 and 2) compared with NC group (5.3 +/- 1.2 ms2 vs. 6.1 +/- 1.3 ms2, and 5.5 +/- 1.6 ms2 vs. 6.2 +/- 1.5 ms2, and 4.6 +/- 1.7 ms2 vs. 6.2 +/- 1.5 ms2, for resting values respectively; 4.7 +/- 1.4 ms2 vs. 5.9 +/- 1.2 ms2, and 4.6 +/- 1.9 ms2 vs. 5.6 +/- 1.7 ms2, and 3.7 +/- 2.1 ms2 vs. 5.6 +/- 1.7 ms2, for stress values respectively; M/F ratio 6/26 vs. 30/14). These differences remained significant even when controlled for age, sex, and body weight. However, patients with DM type 2 (and significantly higher body weight) showed only significant values in mental stress modulus values. There were no specific group effects in the patients with DM in adaptation mechanisms to mental stress compared with the NC group. These findings demonstrate that power spectral examinations at rest are sufficiently reliable to diagnose early alterations in ANS in patients with DM. The spectral analysis technique is sensitive and reliable in investigation of ANS in patients with DM without clinically symptomatic autonomic dysfunction.

Autonomic neuropathy in Type 2 diabetic patients is associated with hyperinsulinaemia and hypertriglyceridaemia

AIMS

To clarify whether parasympathetic neuropathy in Type 2 diabetic patients is associated with features of the insulin resistance syndrome.

METHODS

Blood pressures, glycaemic control (HbA1c), plasma lipids, residual beta-cell function (fasting plasma C-peptide), autonomic nerve function, urinary albumin excretion and glomerular filtration rate (Cr-EDTA clearance) were evaluated in 82 Type 2 diabetic patients (age 63+/-years) 5 years after diagnosis of diabetes.

RESULTS

Parasympathetic neuropathy (an abnormal age corrected E/I ratio) was found in 24/82 (29%) patients. After adjustment for body mass index (BMI), patients with parasympathetic neuropathy had elevated fasting plasma C-peptide (P < 0.001) and triglyceride (Tg) (P < 0.05) levels compared with patients without parasympathetic neuropathy. In addition, the age corrected E/I ratio correlated inversely with Tg (r=-0.31; P<0.01) and fasting plasma C-peptide (r=-0.32; P < 0.01) in the Type 2 diabetic patients.

CONCLUSION

Autonomic neuropathy 5 years after diagnosis of Type 2 diabetes is associated with an unfavourable metabolic risk profile.

A prospective study of orthostatic blood pressure in diabetic patients

To clarify whether orthostatic blood pressure is affected by the type of diabetes, cardiac autonomic neuropathy, and the duration of diabetes, orthostatic blood pressure (passive 90 degrees tilt) was evaluated in 102 patients with insulin dependent diabetes mellitus (IDDM), 51 patients with non-insulin dependent diabetes mellitus (NIDDM), and in 238 control subjects in a first study followed up after 8 to 17 years. The heart rate reaction during deep breathing (E/I ratio) and to tilt (acceleration and brake indices) assessed cardiac autonomic function. In the first study, the lowest systolic blood pressure (LSBP) and the lowest diastolic blood pressure (LDBP) after tilt were significantly lower in IDDM patients compared with NIDDM patients (p < 0.001 for LSBP and p < 0.05 for LDBP) and controls (p < 0.001). LDBP was, however, also significantly lower (p < 0.05) in NIDDM patients than in controls. Hence, although most severe in IDDM, LDBP was disturbed in both types of diabetes. In IDDM, a low E/I ratio was associated with disturbed orthostatic blood pressure. At follow-up examinations, orthostatic blood pressure deteriorated in NIDDM but not in IDDM patients. In conclusion, LSBP and LDBP were impaired in IDDM patients compared with NIDDM and control subjects; however, LDBP was also impaired in NIDDM patients compared with controls. When the duration of diabetes increased, orthostatic blood pressure deteriorated in NIDDM but not in IDDM patients.

Disturbances of autonomic nervous function in primary Sjögren's syndrome

Autonomic nervous function was evaluated by deep breathing [expiration/inspiration (E/I) ratio] and tilt table tests [acceleration (AI) and brake indices (BI)] in 19 patients with primary Sjögren's syndrome (pSS) and in 56 age matched controls. The E/I-ratio and systolic blood pressure (at rest, 1, and 8 min after tilt) were found to be significantly reduced (p < 0.001, p < 0.05, p < 0.01, p < 0.01 respectively) in patients with pSS whereas neither AI, BI nor diastolic blood pressure did differ significantly between patients and controls (NS). The van Bijsterveld's score correlated negatively with the AI (r = -0.77, p< 0.001) as well as the BI (r = -0.60, p < 0.01). No correlations were found between the 3 autonomic nerve function parameters (E/I-ratio, AI, BI) and unstimulated whole sialometry or salivary gland scintigraphy. We conclude that autonomic disturbances, mainly affecting the parasympathetic nerves are associated with pSS.

[Autonomic neuropathy in patients with impaired glucose tolerance]

Impaired glucose tolerance (IGT) is a clinical situation characterized by mild hyperglycemia, which is estimated to afflict 7.8% of the Brazilian population. Diabetic neuropathy is the most common complication in diabetes mellitus and it is related to morbidity and lethality in this disease. The association between IGT and peripheral neuropathy is still a matter of great concern.

PURPOSE AND METHOD

In order to determine if IGT is associated with autonomic neuropathy a cross-sectional study in 44 patients with impaired glucose tolerance test (Group 1) was performed. The patients were compared to 43 control individuals (Group 2). Every patient in each group underwent anamnesis and standardized autonomic tests which consisted of heart frequency test, Valsalva maneuver, postural test and sinus arrhythmia. Routine hematologic exams as well as GTT were also made.

RESULTS

Patients in group 1 had more systemic arterial hypertension, centripetal obesity, fasting and post-feeding hyperglycemia and dyslipidemia when compared with group 2. When we analysed the autonomic tests, the sinus arrhythmia test was abnormal in 54.5% of the patients in group 1 and in 32.5% in group 2 (p = 0.0039) and the Valsalva maneuver was abnormal in 34.1% of group 1 and in 7% of group 2 (p = 0.004). The postural test was not different in both groups (p = 0.334).

CONCLUSION

Our results show that the involvement of the autonomic nervous system was more frequent in patients with IGT when compared to controls. These findings can explain the increased lethality due to vasculopathies observed in this group of patients and also alert physicians to care for patients with impaired glucose tolerance test.

Disturbances of autonomic nervous function in primary Sjögren's syndrome

Autonomic nervous function was evaluated by deep breathing [expiration/inspiration (E/I) ratio] and tilt table tests [acceleration (AI) and brake indices (BI)] in 19 patients with primary Sjögren's syndrome (pSS) and in 56 age matched controls. The E/I-ratio and systolic blood pressure (at rest, 1, and 8 min after tilt) were found to be significantly reduced (p < 0.001, p < 0.05, p < 0.01, p < 0.01 respectively) in patients with pSS whereas neither AI, BI nor diastolic blood pressure did differ significantly between patients and controls (NS). The van Bijsterveld's score correlated negatively with the AI (r = -0.77, p < 0.001) as well as the BI (r = -0.60, p < 0.01). No correlations were found between the 3 autonomic nerve function parameters (E/I-ratio, AI, BI) and unstimulated whole sialometry or salivary gland scintigraphy. We conclude that autonomic disturbances, mainly affecting the parasympathetic nerves are associated with pSS.

Relationships among glomerular filtration rate, albuminuria, and autonomic nerve function in insulin-dependent and non-insulin-dependent diabetes mellitus

The associations among autonomic neuropathy, urinary albumin excretion, and glomerular filtration rate (GFR) measured with 51Cr-EDTA and iohexol clearance were studied in 41 patients with insulin-dependent diabetes mellitus (IDDM) and 15 patients with non-insulin-dependent diabetes mellitus (NIDDM). The study showed that increased urinary albumin excretion was more common in NIDDM than in IDDM. In contrast with IDDM, albuminuria in NIDDM was not related to GFR. Autonomic neuropathy was common in IDDM as well as in NIDDM, and also in patients without nephropathy, but was not connected with hyperfiltration. Low brake index, an ortostatic autonomic index, was associated with nephropathy in NIDDM. Iohexol, a non-ionic contrast medium, was found to be a useful alternative to 51Cr-EDTA for determination of GFR. Moreover, comparison between conventional four-sample plasma clearance and single-sample clearance showed a close correlation. Accordingly, assessment of GFR using a single plasma sample provides reliable results even at high GFR values.

Cutaneous vasomotor responses in young type I diabetic patients

Abnormal skin temperature reactions have been reported in type I diabetic patients. Whether this is due to a primary vascular disturbance or autonomic neuropathy is unclear. The aim of this study was to clarify this issue by evaluating cutaneous circulatory reactions before and after provocation. Seventeen type I diabetic patients and 17 age-matched controls were studied by recording blood flow (laser Doppler technique) on the dorsum of the hand (before, during, and after arterial occlusion), blood flow and skin temperatures on the dorsum of the foot and on the toe (before and after cooling followed by indirect body heating) and autonomic nerve function (heart rate reaction to deep breathing and to tilting). The results showed that before [4.6 +/- 0.5 perfusion units (PU) versus 6.1 +/- 0.7 PU; p = 0.0356] and after arterial occlusion (17.5 +/- 1.6 PU versus 25.3 +/- 1.7 PU; p = 0.0024), hand skin blood flow was significantly lower in patients than in controls. On the dorsum of the foot, skin temperatures was significantly lower in patients than in controls before cooling (29.2 degrees C +/- 0.3 degrees C versus 30.5 degrees C +/- 0.4 degrees C; p = 0.0107) whereas toe temperature and toe blood flow were similar before and after cooling in patients and controls. After body heating, however, toe temperature (after 30 min: 25.2 degrees C +/- 1.4 degrees C versus 30.9 degrees C +/- 1.2 degrees C; p = 0.0022) and toe blood flow (after 30 min: 10.9 +/- 2.5 degrees C versus 22.9 +/- 4.9 PU; p = 0.0313) were significantly lower in patients than in controls, especially in patients with parasympathetic neuropathy (i.e., patients with abnormal heart rate reactions to deep breathing). In conclusion, type I diabetic patients demonstrated a vascular disturbance in their skin that seemed to be exaggerated by parasympathetic neuropathy.

Autonomic neuropathy and cardiovascular risk factors in insulin-dependent and non insulin-dependent diabetes

In 97 IDDM and 64 NIDDM patients aged under 65 years, we evaluated the relationship between autonomic neuropathy (AN) and retinopathy, nephropathy, glycemic control and cardiovascular risk factors. Diabetes duration and HbA1 were significantly higher and body mass index was significantly lower in IDDM patients with AN compared to those without. In NIDDM only age was significantly higher in neuropathic patients. AN was associated with retinopathy in both IDDM (chi2 = 10, P < 0.03) and NIDDM patients (chi2 = 14, P < 0.007), while only in IDDM albumin excretion was significantly higher in patients with AN. Blood pressure (BP) was significantly higher in both IDDM and NIDDM patients with AN compared to those without. There were no differences in smoking and serum lipids between patients with and those without AN. We performed a multiple regression analysis using autonomic score, index of cardiovascular tests impairment, as the dependent variable and age, diabetes duration, body mass index, HbA1, albumin excretion, cholesterolemia, triglyceridemia, systolic BP, and retinopathy as independent variables. With this model in IDDM autonomic score was only related to body mass index (r = -0.29, P < 0.05), to HbA1 (r = 0.46, P < 0.001), and to systolic BP (r = 0.24, P < 0.05), while in NIDDM it was only related to systolic BP (r = 0.54, P < 0.001). In conclusion, AN was related to age in NIDDM, and to diabetes duration and glycemic control in IDDM. AN was associated with retinopathy, with nephropathy (only in IDDM), and with BP levels, but not with dyslipidemia, smoking, or obesity. Excess mortality rate observed in diabetic AN cannot be referred to an association with cardiovascular risk factors.

Blockade of muscarinic transmission increases the frequency of diabetes after low-dose alloxan challenge in the mouse

The diabetogenic action of the beta-cell toxin, alloxan, is transient when administered to mice at a dosage of 50 mg/kg. We examined whether increased cholinergic activity is involved in the compensatory mechanisms. Therefore, following administration of alloxan, methylatropine (32 mumol/kg) was given intraperitoneally once daily for 5 consecutive days. Methyl atropine worsened the degree of hyperglycaemia during the first week after alloxan administration. Recovery from the diabetes mellitus was observed in a substantial number of animals given alloxan without methyl atropine, whereas the risk of developing manifest diabetes was markedly enhanced by methyl atropine. At 35 days after alloxan administration, 33% of the animals, which were given alloxan alone and were diabetic after 4 days, still had diabetes. In contrast, of the animals rendered diabetic by alloxan with concomitant atropinization, 92% remained diabetic throughout the study (p = 0.0145 vs alloxan alone). Glucose-stimulated insulin secretion and pancreatic insulin content were markedly reduced in animals with diabetes while being less reduced in alloxan-injected animals without diabetes. Moreover, in situ hybridization and immunocytochemistry revealed markedly decreased levels of insulin mRNA and number of insulin cells in alloxan-treated animals. With regard to insulin secretion, pancreatic insulin content, insulin mRNA and insulin cell number, the reduction was the same irrespective of whether methyl atropine had been given. Thus, 5 days of atropinization increases the incidence of diabetes following alloxan at 50 mg/kg in mice. We suggest that cholinergic activity protects insulin cells from glucotoxicity during the first week after alloxan administration and therefore, reduces the frequency of diabetes.

Prospective study of autonomic nerve function in type 1 and type 2 diabetic patients: 24 hour heart rate variation and plasma motilin levels disturbed in parasympathetic neuropathy

To clarify the impact of autonomic neuropathy in diabetic patients, we have conducted a prospective study of 58 Type 1 and 51 Type 2 diabetic patients (investigated at baseline, after 4, and after 7 years). In Type 1 diabetic patients, the sympathetic nerve function (orthostatic acceleration and brake indices) and in Type 2 patients, parasympathetic nerve function (R-R interval variation; E/l ratio) deteriorated during 7 years of prospective observation. Symptoms of autonomic neuropathy were associated with signs of autonomic neuropathy (low brake indices) in Type 1 but not in Type 2 diabetic patients. In the latest assessment 24 h ECG recording was performed and blood samples assayed for neuropeptide Y (NPY) and motilin were obtained. Type 1 diabetic patients with parasympathetic neuropathy (abnormal E/l ratio) showed significantly lower SD value (less variation in the R-R intervals; 29 [17] vs 50 [16], [mean (interquartile range)]; p = 0.001) and higher postprandial plasma motilin values (70 [20] pmol l-1 vs 50 [15] pmol l-1; p < 0.01) than patients with normal parasympathetic nerve function. In Type 2 diabetic patients, sympathetic neuropathy (low brake indices) was associated with an increased frequency of ventricular extra systolic beats during 24 h ECG recording (rs = 0.65; p < 0.01). Postprandial plasma NPY levels were not associated with disturbed autonomic nerve function.

Autonomic nerve dysfunction in patients with bolus-specific esophageal dysmotility

The pathogenetic mechanisms causing esophageal dysmotility is not well understood. We examined 13 patients with solid bolus dysphagia in a radiologic barium study including the swallowing of a 14-mm tablet. In all 13 patients the tablet was caught in the proximal or midesophagus. In 8 patients, the entrapment was associated with symptoms (Group 1) whereas in 5 patients (Group 2), no symptoms were reported. All 13 patients together with a control group of 56 healthy, nondysphagic subjects were tested for autonomic nerve function. Autonomic nerve function tests included registration of electrocardiographic R-R interval variation during deep breathing test (E/I ratio), a test of parasympathetic, vagal, nerve function. The results showed that the E/I ratio was significantly lower in patients with symptoms of bolus-specific esophageal dysmotility (-2,19 [1.76]) (median [interquartile range]) compared with patients without symptoms (0.05 [2, 87], p = 0.0192) and controls (-0.25 [1.26], p = 0.0009). In conclusion, symptomatic bolus-specific esophageal dysmotility is associated with vagal nerve dysfunction.

Diabetes mellitus but not impaired glucose tolerance is associated with dysfunction in peripheral nerves

To clarify whether long-term impaired glucose tolerance (IGT) is associated with dysfunction of peripheral and autonomic nerves, age-matched men with IGT and diabetes mellitus were followed prospectively for 12-15 years, when peripheral and autonomic nerve function was assessed. The patients comprised four subgroups: (1) 51 IGT subjects (duration of IGT at least 12-15 years); (2) 35 diabetic patients, with IGT 12-15 years ago, who later developed diabetes; (3) 34 diabetic patients, duration of diabetes at least 12-15 years; and (4) 62 age-matched non-diabetic control subjects. Mean age of the whole study population was 61 +/- 2 years (mean +/- SD), not different in the four groups. Peripheral nerve function tests included nerve conduction velocities, amplitudes, distal latencies, F-reflexes, and sensory perception thresholds for heat, cold, and vibration. Autonomic nerve function tests included the heart rate reaction during deep breathing (expiration to inspiration ratio) and to tilt (acceleration and brake indices). Despite 12-15 years of IGT, peripheral nerve function did not differ between IGT and control subjects, whereas autonomic nerve function deviated; an abnormal expiration to inspiration ratio (a sign of vagal nerve dysfunction) was significantly more common (15/51 versus 5/62; p < 0.01) in IGT than in control subjects. Diabetic patients (groups 2 and 3) showed lower conduction velocities (in general 2-4 m s-1 lower) than IGT and control subjects in all tested nerves. In conclusion, diabetes but not IGT, is associated with peripheral nerve dysfunction.

Glutamic acid decarboxylase antibodies, autonomic nerve antibodies and autonomic neuropathy in diabetic patients

To clarify whether GAD-ab are associated with diabetic autonomic neuropathy and/or complement fixing antibodies against sympathetic ganglia, adrenal medulla, and vagus nerve, we examined 133 diabetic patients (95 with IDDM). GAD-ab were determined by a radioligand binding assay using in vitro expression of recombinant GAD-65 whereas sympathetic ganglia antibodies, adrenal medulla antibodies, vagus nerve, and ICA were evaluated by indirect immunofluorescence assays. Autonomic nerve function was evaluated by objective tests (heart rate reactions to deep breathing and to tilt). In the total material of 133 patients, GAD-ab were detected in 36 patients, all of whom had IDDM. The frequency of GAD-ab was similar (38%) in IDDM patients with and without signs of autonomic neuropathy (21 of 55 vs 15 of 40). In addition, there were no significant associations between GAD-ab and autonomic nerve antibodies; GAD-ab were detected in 9 of 21 (43%) of patients with and in 27 of 112 (24%) of patients without sympathetic ganglia antibodies, in 5 of 15 (33%) of patients with and 31 of 118 (26%) without adrenal medulla antibodies, and in 5 of 15 (33%) with and 31 of 118 (26%) of patients without vagus nerve antibodies. The frequency of ICA, however, was significantly increased in patients with sympathetic ganglia antibodies compared with those without sympathetic ganglia antibodies (10 of 21 [48%] vs 21 of 112 [19%]; p < 0.01). In conclusion, GAD-ab were neither associated with disturbed autonomic nerve function nor with antibodies against autonomic nerve structures.

Effect of metabolic control on autonomic function in obese patients with newly diagnosed type 2 diabetes

To evaluate the effect of diet therapy and physical exercise on autonomic nervous function in newly diagnosed Type 2 diabetes, we followed 83 middle-aged obese patients (48 men, 35 women) for a 15-month period. After a 3-month basic education programme the patients were randomized to one of two groups for comparison of standard treatment given by community health centres (conventionally treated group) and intensive dietary and exercise education (intervention group). Autonomic function was assessed by heart rate variability during deep breathing (expiration/inspiration ratio, E/I), and by systolic blood pressure response to standing up. The intensively treated women (n = 18) had the best blood glucose throughout the study, and this was the only group to show an improvement in E/I ratio (1.19 +/- 0.03 vs 1.30 +/- 0.05, mean +/- SEM, p < 0.05). None of the groups showed any significant change in systolic blood pressure response to standing up. For further analyses, the original groups were combined and thereafter divided into those with declining fasting blood glucose during the intervention phase (n = 39) and into those with no change or increase in blood glucose level (n = 44). The group with improving blood glucose level showed an increase in E/I ratio (1.22 +/- 0.02 vs 1.28 +/- 0.03, p < 0.01) while in the other group E/I ratio remained unchanged (1.21 +/- 0.02 vs 1.20 +/- 0.02). The difference in E/I ratio between these two groups was significant at 15 months (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic nervous function and its relationship to cardiac performance in middle-aged diabetic patients without clinically evident cardiovascular disease

Autonomic nervous function was evaluated in 36 patients with insulin-dependent diabetes mellitus (IDDM), 39 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 48 control subjects, all without clinically evident cardiovascular disease. Valsalva ratio and heart rate variation during deep breathing were lower in both diabetic groups than in the control group. Autonomic nervous function score (ANFS) was more abnormal in patients with IDDM than in control subjects, but was not significantly increased in patients with NIDDM. There was a negative correlation between ANFS and left ventricular diastolic filling evaluated by echocardiography or peak heart rate during exercise in both diabetic groups. There were no correlations between ANFS and left ventricular systolic function at rest or during exercise in any of the groups. In conclusion, autonomic nervous function was abnormal in middle-aged diabetic patients, and it was associated with impaired left ventricular diastolic filling at rest and decreased heart rate response to exercise, but not with left ventricular systolic function.

Autonomic nerve antibodies and autonomic nerve function in type 1 and type 2 diabetic patients

Complement-fixing adrenal medulla (CF-ADM), sympathetic ganglion (CF-SG), and vagal (CF-V) nerve antibodies were determined in diabetic patients. Among 74 patients with Type 1 diabetes, CF-ADM was detected in 7 (10%) cases, CF-SG in 14 (19%) cases, and CF-V in 8 (11%) cases. Among 38 patients with Type 2 diabetes, CF-ADM was detected in 5 (13%) cases, CF-SG in 4 (11%) cases, and CF-V in 6 (16%) cases. There were associations between autonomic nerve antibodies and autonomic nerve function. CF-ADM and/or CF-SG were significantly (P less than 0.002) less prevalent in Type 1 diabetic patients with autonomic neuropathy than in those without [5/44 (11%) vs. 14/30 (47%)] and, in agreement with this, the brake index, a sign of parasympathetic and sympathetic autonomic nerve function, was significantly (P less than 0.005) higher (more normal) in these patients (-0.56 +/- 0.13 vs. -1.04 +/- 0.12). In Type 2 diabetic patients, the E/I ratio, an index of parasympathetic nerve function, was significantly (P less than 0.03) lower (more abnormal) in those with CF-V than in those without (-1.81 +/- 0.17 vs. -1.20 +/- 0.11). In conclusion, the frequency of sympathetic nerve antibodies was decreased in Type 1 diabetic patients with autonomic neuropathy, while in Type 2 diabetic patients parasympathetic nerve antibodies were related to severe parasympathetic neuropathy.