Bilateral atrophy of the extensor digitorum brevis muscle might be a useful sign for diagnosing diabetic polyneuropathy in Japanese men who do not sit in the traditional "seiza" style.

AIMS/INTRODUCTION: As the extensor digitorum brevis muscle is a small muscle in the most distal part of the legs, its atrophy (EDBA) might reflect symmetric polyneuropathy (SPN). We aimed to clarify the EDBA-related factors and the usefulness of bilateral EDBA detection for diagnosing SPN, especially diabetic SPN (DSPN). MATERIALS AND METHODS: In 1,893 participants from the Japanese general population (investigation I) and 133 established diabetes patients (investigation II), relationships between EDBA and various factors including the traditional sitting style called "seiza'" (kneeling and sitting on one's heels) were investigated. Analyses were carried out by univariate and multivariate analysis, and SPN or DSPN was diagnosed by the criteria of "Probable DSPN" of the Toronto Consensus. The validity of EDBA detection for diagnosing SPN/DSPN was also evaluated. RESULTS: Investigation I: EDBA was more prevalent in women than men (44% vs 20%). Significant EDBA-related factors were aging and seiza habit regardless of sex. Male-specific EDBA-related factors were SPN and known diabetes. In men without seiza habit, EDBA was significantly associated with SPN regardless of diabetes, so EDBA seemed to be a useful sign for diagnosing SPN/DSPN. Investigation II: In men, DSPN was more prevalent in the EDBA group than the non-EDBA group (71% vs 33%). Sensitivity, specificity, positive predictive value and kappa coefficient of EDBA detection for diagnosing DSPN were 44, 87, 67% and 0.323, showing fair agreement. CONCLUSIONS: EDBA detection might be a useful method to screen for distal symmetric polyneuropathy, such as DSPN in men, although the exclusion of individuals with seiza habit is necessary to improve accuracy.

Clinical Utility of the Meal Tolerance Test in the Care of Patients with Type 2 Diabetes Mellitus.

Objective The measurement of C-peptide immunoreactivity (CPR) is essential for evaluating the pancreatic ß-cell function and selecting appropriate therapeutic agents in patients with diabetes mellitus. The meal tolerance test (MTT) is simple to administer physiological insulin-stimulating test. Previous studies have reported that several CPR-related indices are useful markers for predicting insulin requirement in type 2 diabetes. In the present study, we investigated the serum CPR response during the MTT in hospitalized patients with type 2 diabetes mellitus in order to clarify the clinical utility of the MTT. Methods We performed the MTT using a test meal with timed measurements of the serum CPR level based on the oral glucose tolerance test over 180 minutes and tested the correlation of various CPR-related indices and clinical factors in patients with type 2 diabetes mellitus. Patients The subjects were patients with type 2 diabetes mellitus who had been admitted to our hospital for diabetes management and education. The final study population consisted of 68 patients. Results The fasting CPR level was correlated with the 24-hour urinary CPR excretion and body mass index. The serum CPR level at 120 minutes in the MTT was strongly correlated with the area under the curve of CPR during the MTT. The patients who needed insulin therapy at 6 months after hospitalization showed a significant lower incremental CPR value from 0 to 120 minutes in the MTT than those who did not need insulin therapy. Conclusion The plasma C-peptide levels at 0 and 120 minutes in the MTT provide essential information for the clinical management of patients with type 2 diabetes mellitus.

Clinical polyneuropathy does not increase with prediabetes or metabolic syndrome in the Japanese general population.

AIMS/INTRODUCTION: The prevalence of clinical polyneuropathies (ClinPNs) or nerve conduction abnormality (NCA) in the groups stratified by glucose tolerance, individual components of metabolic syndrome (metabolic syndrome [MetS] components: hypertension, dyslipidemia, obesity) and MetS defined by the International Diabetes Federation consensus was investigated in the Japanese general population. Factors associated with ClinPN and NCA were also identified. MATERIALS AND METHODS: A total of 625 examinees of regional medical checkup programs were recruited to this cross-sectional study. ClinPNs were diagnosed by the Toronto Consensus. NCA was judged by at least one bilateral abnormality of sural nerve action potential amplitude or conduction velocity measured by a point-of-care nerve conduction device (DPNCheck). Clinical factors associated with ClinPNs or NCA were examined by multiple logistic regression analysis. Deteriorating factors of sural nerve action potential amplitude or conduction velocity values were also investigated in participants without diabetes (n = 550). RESULTS: As for glucose tolerance, ClinPNs or NCA significantly increased only in known diabetes patients compared with other groups. There was no difference between prediabetes and the normal group. The prevalence of ClinPNs and NCA was not significantly related to MetS or MetS' components, except for frequent NCA in obesity. The factors significantly associated with both NCA and ClinPNs were smoking and known diabetes. In non-diabetic participants, aging, tall height and hypertension were significant deteriorating factors of nerve conduction functions. CONCLUSIONS: In Japan, ClinPNs and NCA were increased in known diabetes patients, but did not increase in participants with prediabetes, MetS and MetS' components. Smoking and known diabetes were factors significantly associated with ClinPNs or NCA. Hypertension might be a modifiable deteriorating factor of nerve function.

Difference in normal limit values of nerve conduction parameters between Westerners and Japanese people might need to be considered when diagnosing diabetic polyneuropathy using a Point-of-Care Sural Nerve Conduction Device (NC-stat®/DPNCheck™).

AIM/INTRODUCTION: Studies on a novel point-of-care device for nerve conduction study called DPNCheck have been limited to Westerners. We aimed to clarify Japanese normal limits of nerve action potential amplitude (Amp) and conduction velocity by DPNCheck (investigation I), and the validity of DPNCheck to identify diabetic symmetric sensorimotor polyneuropathy (DSPN; investigation II). MATERIALS AND METHODS: For investigation I, 463 non-neuropathic Japanese participants underwent DPNCheck examinations. Regression formulas calculating the normal limits of Amp and conduction velocity (Japanese regression formulas [JRF]) were determined by quantile regression and then compared with regression formulas of individuals from the USA (USRF). For investigation II, in 92 Japanese diabetes patients, 'probable DSPN' was diagnosed and nerve conduction abnormalities (NCA1: one or more abnormalities, and NCA2: two abnormalities in Amp and conduction velocity) were determined. Validity of NCAs to identify 'probable DSPN' was evaluated by determining sensitivity, specificity, reproducibility (kappa-coefficient) and the area under the curve of receiver operating characteristic curves. RESULTS: For investigation I, JRF was different from USRF, and normal limits by JRF were higher than that of USRF. The prevalence of Amp abnormality calculated by JRF was significantly higher than that of USRF. For investigation II, the sensitivity, specificity and reproducibility of NCA1 and NCA2 judged from JRF were 85%, 86% and 0.57, and 43%, 100% and 0.56, respectively. These values of JRF were higher than those of USRF. The area under the curve of JRF (0.89) was larger than USRF (0.82). CONCLUSIONS: A significant difference in the normal limits of nerve conduction parameters by DPNCheck between Japanese and USA individuals was suggested. Validity to identify DSPN of NCAs might improve by changing the judgment criteria from USRF to JRF.