Empagliflozin add-on therapy to closed-loop insulin delivery in type 1 diabetes: a 2 × 2 factorial randomized crossover trial.

There is a need to optimize closed-loop automated insulin delivery in type 1 diabetes. We assessed the glycemic efficacy and safety of empagliflozin 25 mg d-1 as add-on therapy to insulin delivery with a closed-loop system. We performed a 2 × 2 factorial randomized, placebo-controlled, crossover two-center trial in adults, assessing 4 weeks of closed-loop delivery versus sensor-augmented pump (SAP) therapy and empagliflozin versus placebo. The primary outcome was time spent in the glucose target range (3.9-10.0 mmol l-1). Primary comparisons were empagliflozin versus placebo in each of closed-loop or SAP therapy; the remaining comparisons were conditional on its significance. Twenty-four of 27 randomized participants were included in the final analysis. Compared to placebo, empagliflozin improved time in target range with closed-loop therapy by 7.2% and in SAP therapy by 11.4%. Closed-loop therapy plus empagliflozin improved time in target range compared to SAP therapy plus empagliflozin by 6.1% but by 17.5% for the combination of closed-loop therapy and empagliflozin compared to SAP therapy plus placebo. While no diabetic ketoacidosis or severe hypoglycemia occurred during any intervention, uncomplicated ketosis events were more common on empagliflozin. Empagliflozin 25 mg d-1 added to automated insulin delivery improves glycemic control but increases ketone concentration and ketosis compared to placebo.

Corneal Confocal Microscopy Predicts the Development of Diabetic Neuropathy: A Longitudinal Diagnostic Multinational Consortium Study.

OBJECTIVE: Corneal nerve fiber length (CNFL) has been shown in research studies to identify diabetic peripheral neuropathy (DPN). In this longitudinal diagnostic study, we assessed the ability of CNFL to predict the development of DPN. RESEARCH DESIGN AND METHODS: From a multinational cohort of 998 participants with type 1 and type 2 diabetes, we studied the subset of 261 participants who were free of DPN at baseline and completed at least 4 years of follow-up for incident DPN. The predictive validity of CNFL for the development of DPN was determined using time-dependent receiver operating characteristic (ROC) curves. RESULTS: A total of 203 participants had type 1 and 58 had type 2 diabetes. Mean follow-up time was 5.8 years (interquartile range 4.2-7.0). New-onset DPN occurred in 60 participants (23%; 4.29 events per 100 person-years). Participants who developed DPN were older and had a higher prevalence of type 2 diabetes, higher BMI, and longer duration of diabetes. The baseline electrophysiology and corneal confocal microscopy parameters were in the normal range but were all significantly lower in participants who developed DPN. The time-dependent area under the ROC curve for CNFL ranged between 0.61 and 0.69 for years 1-5 and was 0.80 at year 6. The optimal diagnostic threshold for a baseline CNFL of 14.1 mm/mm2 was associated with 67% sensitivity, 71% specificity, and a hazard ratio of 2.95 (95% CI 1.70-5.11; P < 0.001) for new-onset DPN. CONCLUSIONS: CNFL showed good predictive validity for identifying patients at higher risk of developing DPN ∼6 years in the future.

Reducing the need for carbohydrate counting in type 1 diabetes using closed-loop automated insulin delivery (artificial pancreas) and empagliflozin: A randomized, controlled, non-inferiority, crossover pilot trial.

AIM: To assess whether adding empagliflozin to closed-loop automated insulin delivery could reduce the need for carbohydrate counting in type 1 diabetes (T1D) without worsening glucose control. MATERIALS AND METHODS: In an open-label, crossover, non-inferiority trial, 30 adult participants with T1D underwent outpatient automated insulin delivery interventions with three random sequences of prandial insulin strategy days: carbohydrate counting, simple meal announcement (no carbohydrate counting) and no meal announcement. During each sequence of prandial insulin strategies, participants were randomly assigned empagliflozin (25 mg/day) or not, and crossed over to the comparator. Mean glucose for carbohydrate counting without empagliflozin (control) was compared with no meal announcement with empagliflozin (in the primary non-inferiority comparison) and simple meal announcement with empagliflozin (in the conditional primary non-inferiority comparison). RESULTS: Participants were aged 40 ± 15 years, had 27 ± 15 years diabetes duration and HbA1c of 7.6% ± 0.7% (59 ± 8 mmol/mol). The system with no meal announcement and empagliflozin was not non-inferior (and thus reasonably considered inferior) to the control arm (mean glucose 10.0 ± 1.6 vs. 8.5 ± 1.5 mmol/L; non-inferiority p = .94), while simple meal announcement and empagliflozin was non-inferior (8.5 ± 1.4 mmol/L; non-inferiority p = .003). Use of empagliflozin on the background of automated insulin delivery with carbohydrate counting was associated with lower mean glucose, corresponding to a 14% greater time in the target range. While no ketoacidosis was observed, mean fasting ketones levels were higher on empagliflozin (0.22 ± 0.18 vs. 0.13 ± 0.11 mmol/L; p < .001). CONCLUSIONS: Empagliflozin added to automated insulin delivery has the potential to eliminate the need for carbohydrate counting and improves glycaemic control in conjunction with carbohydrate counting, but does not allow for the elimination of meal announcement.

The Prevalence of Autoimmune Diseases in Longstanding Diabetes: Results from the Canadian Study of Longevity in Adults with Type 1 Diabetes.

OBJECTIVE: We aimed to determine the prevalence of autoimmune diseases (e.g. thyroid disease, celiac disease, etc) in Canadians with longstanding type 1 diabetes (T1D) and to explore sex-specific differences and the association with complications. METHODS: Cross-sectional data were analyzed in an exploratory secondary analysis from the Canadian Study of Longevity in Type 1 Diabetes, a nationwide registry of people with T1D of at least 50 years' duration. In total, 374 participants provided self-reported questionnaire data and physician-reported laboratory results. Student's t-test, the Wilcoxon rank-sum test, the χ2 test and logistic regression were used to identify associations with autoimmune diseases. RESULTS: The 374 participants had a median T1D duration of 53 years (interquartile range, 51 to 58) and a median age of onset of 11 years (6 to 16), and 57.1% were females. Females had a greater prevalence of autoimmune diseases (60.6% vs 34.4%, p<0.001). Thyroid disease was most prevalent (41%, 153/374), especially in females (51.6% vs 26.9%), and the prevalence of 1 or more autoimmune disease was 49.3% (184/374). Autoimmune disease was associated with lower odds of cardiovascular disease (CVD)-odds ratio [OR] 0.61, 95% confidence interval [CI] 0.37 to 1.00 for thyroid autoimmune disease and OR 0.34 (95% CI 0.12 to 0.93) for nonthyroid autoimmune disease, both compared to those without autoimmune disease (p=0.033). Autoimmune diseases were not associated with the presence of nephropathy, neuropathy or retinopathy. CONCLUSIONS: Lifetime risk of autoimmune disease in longstanding T1D approaches 50%, is greater in females and is driven by thyroid disease. The probability of diabetes complications, such as CVD, was lower in those with autoimmune disease, which was driven mostly by nonthyroid autoimmune diseases.

Vasopressin associated with renal vascular resistance in adults with longstanding type 1 diabetes with and without diabetic kidney disease.

OBJECTIVE: Arginine vasopressin (AVP) and its surrogate, copeptin, have been implicated in diabetic kidney disease (DKD) pathogenesis, which develops in a subset of people with longstanding type 1 diabetes, but not in others (DKD Resistors). We hypothesized that patients with DKD would exhibit higher copeptin concentrations vs. DKD Resistors. METHODS: Participants with type 1 diabetes (n = 62, duration ≥50 years) were stratified into 42 DKD Resistors and 20 with DKD (eGFR ≤60 mL/min/1.73m2 or ≥30 mg/day urine albumin), and age/sex-matched controls (HC, n = 74) were included. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were calculated by inulin and p-aminohippurate clearance before and after angiotensin II (ang II) infusion. Renal vascular resistance (RVR) was calculated as mean arterial pressure/renal blood flow. Plasma copeptin, renin, aldosterone, neutrophil gelatinase-associated lipocalin (NGAL), and urea concentrations were measured, along with 24-h urine volume. RESULTS: DKD resistors had lower copeptin (95% CI: 4.0 [3.4-4.8] pmol/l) compared to DKD (5.8 [4.5-7.6] pmol/l, p = 0.02) and HC (4.8 [4.1-5.5] pmol/l, p = 0.01) adjusting for age, sex and HbA1c. In type 1 diabetes, higher copeptin correlated with lower GFR (r: -0.32, p = 0.01) and higher renin concentration (r: 0.40, p = 0.002) after multivariable adjustments. These relationships were not evident in HC. Copeptin inversely associated with RVR change following exogenous ang II only in participants with type 1 diabetes (ß ±â€¯SE: -6.9 ±â€¯3.4, p = 0.04). CONCLUSIONS: In longstanding type 1 diabetes, copeptin was associated with intrarenal renin-angiotensin-aldosterone system (RAAS) activation and renal hemodynamic function, suggesting interplay between AVP and RAAS in DKD pathogenesis.

Analysis of Prevalence, Magnitude and Timing of the Dawn Phenomenon in Adults and Adolescents With Type 1 Diabetes: Descriptive Analysis of 2 Insulin Pump Trials.

OBJECTIVES: To better understand the dawn phenomenon in type 1 diabetes, we sought to determine its prevalence, timing and magnitude in studies specifically designed to assess basal insulin requirements in patients using insulin pumps. METHODS: Thirty-three participants from 2 sensor-augmented insulin pump studies were analyzed. Twenty participants were obtained from a methodologically ideal semiautomated basal analysis trial in which basal rates were determined from repeated fasting tests (the derivation set) and 13 from an artificial pancreas trial in which duration of fasting was variable (the "confirmation" set). Prevalence was determined for the total cohort and for individual trials using the standard definition of an increase in insulin exceeding 20% and lasting ≥90 minutes. Among cases, time of onset and percent change in the magnitude of basal delivery were determined. RESULTS: Seventeen participants (52%) experienced the dawn phenomenon (11 of 20 [55%] in the derivation set and 6 of 13 [46%] in the confirmation set). Time of onset was 3 AM (interquartile range [IQR], 3 to 4:15 AM) in the derivation set and 3 AM (IQR, 3 to 4 AM) in the confirmation set. The magnitude of the dawn phenomenon was a 58.1% (IQR, 28.8% to 110.6%) increase in insulin requirements in the derivation set and 65.5% (IQR, 45.6% to 87.4%) in the confirmation set. CONCLUSIONS: The dawn phenomenon occurs in approximately half of patients with type 1 diabetes; when present, it has predictable timing of onset (generally 3 AM) and a substantial, but highly variable, magnitude. These findings imply that optimization of glycemic control requires clinical emphasis on fasted overnight basal insulin assessment.

Sex differences in neuropathy & neuropathic pain: A brief report from the Phase 2 Canadian Study of Longevity in Type 1 Diabetes.

To evaluate previous results from a questionnaire-based study, we studied objective neuropathy measures to determine sex differences in the prevalence of neuropathy and neuropathic pain in longstanding type 1 diabetes. Despite better neuropathy measures in females compared to males, we confirmed a trend towards higher neuropathic pain in females.

Estimating GFR by Serum Creatinine, Cystatin C, and ß2-Microglobulin in Older Adults: Results From the Canadian Study of Longevity in Type 1 Diabetes.

INTRODUCTION: Glomerular filtration rate (GFR) is routinely used for clinical assessment of kidney function. However, the accuracy of estimating equations in older adults is uncertain. METHODS: In 66 adults with ≥50 years type 1 diabetes (T1D) duration and 73 nondiabetic controls from age/sex-matched subgroups (65 ± 8 years old and 77[55%] were women) we evaluated the performance of estimated GFR (eGFR) by creatinine (Modification of Diet and Renal Disease [MDRD], Chronic Kidney Disease-Epidemiology [CKD-EPI]cr), cystatin C (CKD-EPIcys, CKD-EPIcr-cys), and ß2-microglobulin (ß2M) compared with measured GFR by inulin clearance (mGFR). Performance was evaluated using metrics of bias (mean difference), precision (SD), and accuracy (proportion of eGFR that differed by >20% of mGFR). RESULTS: Mean mGFR was 104 ± 18 ml/min per 1.73 m2 (range: 70-154 ml/min per 1.73 m2) and was not different between T1D and controls (103 ± 17 vs. 105 ± 19 ml/min per 1.73 m2, P = 0.39). All equations significantly underestimated mGFR (bias: -15 to -30 ml/min per 1.73 m2, P < 0.001 for all comparisons) except for ß2M, which had bias of 1.9 ml/min per 1.73 m2 (P = 0.61). Bias was greatest in cystatin C-based equations. Precision was lowest for ß2M (SD: 43.5 ml/min per 1.73 m2, P < 0.001 for each comparison). Accuracy was lowest for CKD-EPIcysC (69.1%, P < 0.001 for each comparison). Cystatin C-based equations demonstrated greater bias and lower accuracy in older age subgroups (<60, 60-69, ≥70 years). All equations demonstrated greater bias across higher ranges of mGFR (60-89, 90-119, ≥120 ml/min per 1.73 m2). Results were similar between T1D and controls except that ß2M had lower performance in T1D. CONCLUSION: Better estimates of GFR in older adults are needed for research and clinical practice, as this subgroup of the population has an amplified risk for the development of chronic kidney disease (CKD) that requires accurate GFR estimation methods.

Elevated plasma cyclic guanosine monophosphate may explain greater efferent arteriolar tone in adults with longstanding type 1 diabetes: A brief report.

Cyclic guanosine monophosphate (cGMP) influences intrarenal hemodynamics in animal models, but the relationship between cGMP and renal function in adults with type 1 diabetes (T1D) remains unclear. In this study, plasma cGMP correlated with efferent arteriolar resistance, effective renal plasma flow, and renal vascular resistance in adults with T1D.

Risk factors for diabetic kidney disease in adults with longstanding type 1 diabetes: results from the Canadian Study of Longevity in Diabetes.

Objectives: Diabetic kidney disease (DKD) is an independent predictor of cardiovascular morbidity and mortality in type 1 diabetes (T1D). We aimed to explore clinical and biochemical factors, including the achievement of American Diabetes Association (ADA) recommended targets associated with DKD in people living with T1D for ≥50 years. Methods: This was a post hoc analysis of a cross-sectional study of 75 participants enrolled in the Canadian Study of Longevity in T1D. We explored diabetes-related complications, including neuropathy, retinopathy, cardiovascular disease, and DKD. Study participants were dichotomized based on the achievement of ADA recommended targets as the low-target group (achieving ≤4 targets, n = 31) and high-target group (achieving >4 targets, n = 44). The outcome of interest was DKD defined by estimated glomerular filtration rate (eGFR) values <60/mL/min/1.73 m2 and/or 24-h albumin excretion >30 mg. Multivariable logistic regression models were employed to estimate odds ratios (ORs) for DKD with 95% confidence intervals (CIs). Results: Of the 75 participants with prolonged T1D duration (45% male, mean age 66 years), 25 participants had DKD and 50 did not. There was no statistical difference between the high- and low-target groups in terms of age and body mass index. eGFR was significantly higher and the prevalence of diabetic retinopathy was significantly lower in the high-target group. Older age at diagnosis of T1D and lower frequency component to high-frequency component ratio increased the odds of having DKD. Conclusions: In adults with prolonged T1D duration, older age at diagnosis and lower heart rate variability may be associated with DKD.

The relationships between markers of tubular injury and intrarenal haemodynamic function in adults with and without type 1 diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: Our aim was to define the relationships between plasma biomarkers of kidney injury and intrarenal haemodynamic function (glomerular filtration rate [GFR], effective renal plasma flow [ERPF], renal vascular resistance [RVR]) in adults with type 1 diabetes (T1D). METHODS: The study sample comprised patients with longstanding T1D (duration ≥50 years), among whom 44 were diabetic kidney disease (DKD) resistors (eGFR >60 mL/min/1.73 m2 and <30 mg/d urine albumin excretion) and 22 had DKD, in addition to 73 control participants. GFRINULIN and ERPFPAH were measured, RVR was calculated, and afferent (RA )/efferent (RE ) areteriolar resistances were derived from Gomez equations. Plasma neutrophil gelatinase-associated lipocalin (NGAL), ß2 microglobulin (B2M), osteopontin (OPN) and uromodulin (UMOD) were measured using immunoassay kits from Meso Scale Discovery. RESULTS: Plasma NGAL, B2M and OPN were higher and UMOD was lower in DKD patients vs DKD resistors and non-diabetic controls. In participants with T1D, plasma NGAL inversely correlated with GFR (r = -0.33; P = 0.006) and ERPF (r = -0.34; P = 0.006), and correlated positively with RA (r = 0.26; P = 0.03) and RVR (r = 0.31; P = 0.01). In participants without T1D, NGAL and B2M inversely correlated with GFR (NGAL r = -0.18; P = 0.13 and B2M r = -0.49; P < 0.0001) and with ERPF (NGAL r = -0.19; P = 0.1 and B2M r = -0.42; P = 0.0003), and correlated positively with RA (NGAL r = 0.19; P = 0.10 and B2M r = 0.3; P = 0.01) and with RVR (NGAL r = 0.20; P = 0.09 and B2M r = 0.34; P = 0.003). Differences were significant after adjusting for age, sex, HbA1c, SBP and LDL. There were statistical interactions between T1D status, B2M and intrarenal haemodynamic function (P < 0.05). CONCLUSIONS: Elevated NGAL relates to intrarenal haemodynamic dysfunction in T1D, whereas elevated NGAL and B2M relate to intrarenal haemodynamic dysfunction in adults without T1D. These data may define a diabetes-specific interplay between tubular injury and intrarenal haemodynamic dysfunction.

Retinopathy and RAAS Activation: Results From the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: The importance of renin-angiotensin-aldosterone system (RAAS) activation in retinopathy for long-standing diabetes is not well understood. We determined retinopathy stage and evaluated associations with other vascular complications before and after physiological RAAS activation in adults with long-standing (≥50 years duration) type 1 diabetes. RESEARCH DESIGN AND METHODS: Participants underwent retinal examination by digital funduscopic photography and optical coherence tomography and were classified as having nonproliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), or no diabetic retinopathy (NDR) with or without diabetic macular edema (DME). Neuropathy was measured by clinical neuropathy examination scores, electrophysiologically, and by corneal confocal microscopy. Renal function was measured by inulin and para-aminohippurate clearance methods. Arterial stiffness was measured by applanation tonometry. Renal function, blood pressure, and arterial stiffness were measured before and after RAAS activation with angiotensin II (ANGII). Associations were determined using linear regression. RESULTS: Twelve (16%) of the 75 participants had NDR, 24 (32%) had NPDR, and 39 (52%) had PDR. A low overall prevalence of DME (4%) was observed. Those with PDR had worse nerve function and reduced corneal nerve density, were more likely to have macrovascular disease, and had increased arterial stiffness in response to ANGII compared with those with NPDR or NDR. Prevalence of kidney disease or renal hemodynamic function did not differ by retinopathy status. CONCLUSIONS: PDR was associated with neuropathy severity and cardiovascular and peripheral vascular disease. In those with PDR, RAAS activation may be linked to vascular stiffening, an effect that persists in long-standing type 1 diabetes.

Atherosclerosis and Microvascular Complications: Results From the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: Type 1 diabetes carries a significant risk for cardiovascular mortality, but it is unclear how atherosclerosis associates with microvascular complications. We aimed to determine the relationships between atherosclerotic burden and neuropathy, retinopathy, and diabetic kidney disease (DKD) in adults with a ≥50-year history of type 1 diabetes. RESEARCH DESIGN AND METHODS: Adults with type 1 diabetes (n = 69) underwent coronary artery calcification (CAC) volume scoring by wide-volume computerized tomography. Microvascular complications were graded as follows: neuropathy by clinical assessment, electrophysiology, vibration and cooling detection thresholds, heart rate variability, and corneal confocal microscopy; retinopathy by ultra-wide-field retinal imaging; and DKD by renal hemodynamic function measured by inulin and para-aminohippurate clearance at baseline and after intravenous infusion of angiotensin II. The cohort was dichotomized to high (≥300 Agatston units [AU]) or low (<300 AU) CAC and was stratified by diabetes status. A comparator group without diabetes (n = 73) matched for age and sex also underwent all study procedures except for retinal imaging. RESULTS: CAC scores were higher in participants with type 1 diabetes (median Agatston score 1,000 [interquartile range = 222, 2,373] AU vs. 1 [0.75] AU in comparators, P < 0.001). In participants with type 1 diabetes, high CAC scores associated with markers of neuropathy and retinopathy, but not with DKD, or renal hemodynamic function at baseline or in response to angiotensin II. CONCLUSIONS: The presence of high CAC in adults with longstanding type 1 diabetes was associated with large nerve fiber neuropathy and retinopathy but not with renal hemodynamic function, suggesting that neuropathy, retinopathy, and macrovascular calcification share common risk factors.

Corneal confocal microscopy for identification of diabetic sensorimotor polyneuropathy: a pooled multinational consortium study.

AIMS/HYPOTHESIS: Small cohort studies raise the hypothesis that corneal nerve abnormalities (including corneal nerve fibre length [CNFL]) are valid non-invasive imaging endpoints for diabetic sensorimotor polyneuropathy (DSP). We aimed to establish concurrent validity and diagnostic thresholds in a large cohort of participants with and without DSP. METHODS: Nine hundred and ninety-eight participants from five centres (516 with type 1 diabetes and 482 with type 2 diabetes) underwent CNFL quantification and clinical and electrophysiological examination. AUC and diagnostic thresholds were derived and validated in randomly selected samples using receiver operating characteristic analysis. Sensitivity analyses included latent class models to address the issue of imperfect reference standard. RESULTS: Type 1 and type 2 diabetes subcohorts had mean age of 42 ± 19 and 62 ± 10 years, diabetes duration 21 ± 15 and 12 ± 9 years and DSP prevalence of 31% and 53%, respectively. Derivation AUC for CNFL was 0.77 in type 1 diabetes (p < 0.001) and 0.68 in type 2 diabetes (p < 0.001) and was approximately reproduced in validation sets. The optimal threshold for automated CNFL was 12.5 mm/mm2 in type 1 diabetes and 12.3 mm/mm2 in type 2 diabetes. In the total cohort, a lower threshold value below 8.6 mm/mm2 to rule in DSP and an upper value of 15.3 mm/mm2 to rule out DSP were associated with 88% specificity and 88% sensitivity. CONCLUSIONS/INTERPRETATION: We established the diagnostic validity and common diagnostic thresholds for CNFL in type 1 and type 2 diabetes. Further research must determine to what extent CNFL can be deployed in clinical practice and in clinical trials assessing the efficacy of disease-modifying therapies for DSP.

Sex differences in neuropathic pain in longstanding diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes.

AIM: Neuropathy and neuropathic pain are common complications of type 1 diabetes (T1D). We aimed to determine if sex-specific differences in neuropathic pain are present in adults with longstanding T1D. METHODS: Canadians with ≥50 years of T1D (n = 361) completed health history questionnaires that included assessment of neuropathy (defined by Michigan Neuropathy Screening Instrument questionnaire components ≥3; NEUROPATHYMNSI-Q) and neuropathic pain. Multivariable logistic regression was used to determine sex-differences in neuropathic pain controlling for neuropathy. RESULTS: Participants had mean age 66 ±â€¯9 years, median diabetes duration 53[51,58] years, mean HbA1c 7.5 ±â€¯1.0%, and 207(57%) were female. Neuropathic pain was present in 128(36%) of all participants, more prevalent among those with NEUROPATHYMNSI-Q compared to those without [96(63%) vs. 31(15%), p < 0.001], and more prevalent in females compared to males [87(42%) vs. 41(27%), p = 0.003]. Independent of the presence of NEUROPATHYMNSI-Q and other factors, female sex was associated with the presence of neuropathic pain [OR 2.68 (95% CI 1.4-5.0), p = 0.002]. CONCLUSIONS: We demonstrated a novel sex-specific difference in neuropathic pain in females compared to males with longstanding T1D, independent of the presence of neuropathy. Further research using more objective measures of neuropathy than the MNSI is justified to further understand this sex-specific difference.

Validity of a point-of-care nerve conduction device for polyneuropathy identification in older adults with diabetes: Results from the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: Point-of-care nerve conduction devices (POCD) have been studied in younger patients and may facilitate screening for polyneuropathy in non-specialized clinical settings. However, performance may be impaired with advanced age owing to age-related changes in nerve conduction. We aimed to evaluate the validity of a POCD as a proxy for standard nerve conduction studies (NCS) in older adults with type 1 diabetes (T1D). METHODS: Sural nerve amplitude potential (AMP) and sural nerve conduction velocity (CV) was measured in 68 participants with ≥ 50 years T1D duration and 71 controls (from age/sex-matched subgroups) using POCD and NCS protocols. Agreement was determined by the Bland-Altman method, and validity was determined by receiver operating characteristic curves. RESULTS: T1D were 53% female, aged 66±8yr and had diabetes duration 54yr[52,58]. Controls were 56%(p = 0.69) female and aged 65±8yr(p = 0.36). Mean AMPPOCD and CVPOCD for the 139 participants was 7.4±5.8µV and 45.7±11.2m/s and mean AMPNCS and CVNCS was 7.2±6.1µV and 43.3±8.3m/s. Mean difference of AMPPOCD-AMPNCS was 0.3±3.8µV and was 2.3±8.5m/s for CVPOCD-CVNCS. A AMPPOCD of ≤6µV had 80% sensitivity and 80% specificity for identifying abnormal AMPNCS, while a CVPOCD of ≤44m/s had 81% sensitivity and 82% specificity to identify abnormal CVNCS. Abnormality in AMPPOCD or CVPOCD was associated with 87% sensitivity, while abnormality in both measures was associated with 97% specificity for polyneuropathy identification. CONCLUSIONS: The POCD has strong agreement and diagnostic accuracy for identification of polyneuropathy in a high-risk subgroup and thus may represent a sufficiently accurate and rapid test for routinely detecting those with electrophysiological dysfunction.

Adiposity Impacts Intrarenal Hemodynamic Function in Adults With Long-standing Type 1 Diabetes With and Without Diabetic Nephropathy: Results From the Canadian Study of Longevity in Type 1 Diabetes.

OBJECTIVE: Central adiposity is considered to be an important cardiorenal risk factor in the general population and in type 1 diabetes. We sought to determine the relationship between central adiposity and intrarenal hemodynamic function in adults with long-standing type 1 diabetes with and without diabetic nephropathy (DN). RESEARCH DESIGN AND METHODS: Patients with type 1 diabetes (n = 66, duration ≥50 years) and age-/sex-matched control subjects (n = 73) were studied. The cohort was stratified into 44 DN Resistors (estimated glomerular filtration rate [eGFR] >60 mL/min/1.73 m2 and <30 mg/day urine albumin) and 22 patients with DN (eGFR ≤60 mL/min/1.73 m2 or ≥30 mg/day urine albumin). Intrarenal hemodynamic function (glomerular filtration rate for inulin [GFRINULIN], effective renal plasma flow for p-aminohippuric acid [ERPFPAH]) was measured. Afferent arteriolar resistance, efferent arteriolar resistance, renal blood flow, renal vascular resistance [RVR], filtration fraction, and glomerular pressure were derived from the Gomez equations. Fat and lean mass were quantified by DXA. RESULTS: Whereas measures of adiposity did not associate with GFRINULIN or ERPFPAH in healthy control subjects, trunk fat mass inversely correlated with GFRINULIN (r = -0.46, P < 0.0001) and ERPFPAH (r = -0.31, P = 0.01) and positively correlated with RVR (r = 0.53, P = 0.0003) in type 1 diabetes. In analyses stratified by DN status, greater central adiposity related to lower GFRINULIN values in DN and DN Resistors, but the relationships between central adiposity and ERPFPAH and RVR were attenuated and/or reversed in patients with DN compared with DN Resistors. CONCLUSIONS: The adiposity-intrarenal hemodynamic function relationship may be modified by the presence of type 1 diabetes and DN, requiring further study of the mechanisms by which adiposity influences renal hemodynamic function.

Renin-angiotensin-aldosterone system activation in long-standing type 1 diabetes.

BACKGROUND: In type 1 diabetes (T1D), adjuvant treatment with inhibitors of the renin-angiotensin-aldosterone system (RAAS), which dilate the efferent arteriole, is associated with prevention of progressive albuminuria and renal dysfunction. Uncertainty still exists as to why some individuals with long-standing T1D develop diabetic kidney disease (DKD) while others do not (DKD resistors). We hypothesized that those with DKD would be distinguished from DKD resistors by the presence of RAAS activation. METHODS: Renal and systemic hemodynamic function was measured before and after exogenous RAAS stimulation by intravenous infusion of angiotensin II (ANGII) in 75 patients with prolonged T1D durations and in equal numbers of nondiabetic controls. The primary outcome was change in renal vascular resistance (RVR) in response to RAAS stimulation, a measure of endogenous RAAS activation. RESULTS: Those with DKD had less change in RVR following exogenous RAAS stimulation compared with DKD resistors or controls (19%, 29%, 31%, P = 0.008, DKD vs. DKD resistors), reflecting exaggerated endogenous renal RAAS activation. All T1D participants had similar changes in renal efferent arteroilar resistance (9% vs. 13%, P = 0.37) irrespective of DKD status, which reflected less change versus controls (20%, P = 0.03). In contrast, those with DKD exhibited comparatively less change in afferent arteriolar vascular resistance compared with DKD resistors or controls (33%, 48%, 48%, P = 0.031, DKD vs. DKD resistors), indicating higher endogenous RAAS activity. CONCLUSION: In long-standing T1D, the intrarenal RAAS is exaggerated in DKD, which unexpectedly predominates at the afferent rather than the efferent arteriole, stimulating vasoconstriction. FUNDING: JDRF operating grant 17-2013-312.

Diabetes Care Disparities in Long-standing Type 1 Diabetes in Canada and the U.S.: A Cross-sectional Comparison.

OBJECTIVE: To assess national differences in diabetes care and quality of life (QOL) between individuals with long-standing type 1 diabetes (≥50 years) in Canada and the U.S. RESEARCH DESIGN AND METHODS: Cross-sectional data from identical surveys administered in the Canadian Study of Longevity in Diabetes and the Joslin Medalist Study, collected in 2013-2016 and 2005-2011, respectively, were compared. Laboratory values and ophthalmic examination were completed by clinical care physicians for Canadians and the Joslin Clinic for Americans. Univariate comparisons and multivariable regression for HbA1c, QOL, insulin pump use, and coronary artery disease (CAD) were performed. Nephropathy, CAD, and peripheral arterial disease (PAD) were self-reported; neuropathy was defined by a Michigan Neuropathy Screening Instrument (Questionnaire component) score ≥3, and proliferative retinopathy was documented from ophthalmic examination. QOL was self-reported on an ordinal scale. RESULTS: Three hundred sixty-one Canadians and 668 Americans had similar ages (mean 65.78 years [SD 8.67] vs. 66.38 years [7.66], P = 0.27) and durations of diabetes (median 53.00 years [interquartile range 51.00, 58.00] vs. 53.00 years [51.00, 57.00], P = 0.51). Canadians had higher HbA1c (mean 7.53% [SD 1.03] [59 mmol/mol] vs. 7.22% [0.98] [55 mmol/mol], P < 0.0001), lower QOL (36.9% vs. 48.7% with "excellent" QOL, P = 0.0002), and less CAD (29.7% vs. 41.2%, P = 0.0003) and insulin pump use (43.3% vs. 55.6%, P = 0.0002). Other complication rates were similar. Residual differences for Canadians compared with Americans remained after adjustment for age, sex, CAD, PAD, education, and relevant a priori selected variables: 0.28% higher HbA1c (P = 0.0004); and odds ratios of 0.68 (95% CI 0.51, 0.90), 0.46 (0.31, 0.68), and 0.71 (0.52, 0.96) for higher QOL, CAD, and insulin pump use, respectively. CONCLUSIONS: Although Canadians and Americans have similar rates of complications other than CAD, further research is required to understand why Canadians have higher HbA1c levels, lower QOL, and less insulin pump use.