In type 1 diabetes, real-time vs. intermittently scanned continuous glucose monitoring improved glycemic control

Visser MM, Charleer S, Fieuws S, et al. Comparing real-time and intermittently scanned continuous glucose monitoring in adults with type 1 diabetes (ALERTT1): a 6-month, prospective, multicentre, randomised controlled trial. Lancet. 2021;397:2275-83. 34089660.

Libre in Inpatient Covid Units

Continuous glucose monitors (CGM) have demonstrated accuracy in outpatients and were accurate with pilot data using blinded systems in inpatients. Libre CGMs were approved and donated to hospitalsfor use during the COVID-19 to minimize exposure and PPE use. We made a prospective plan to assess accuracy of the Libre on inpatients admitted to COVID units during an initial “validation phase”. Fingerstick blood glucose (FSBG) was checked for the first three days after placing the sensor and compared to Libre values within the next 1–15 minutes. Patients were instructed to scan the sensor after each FSBG, and at other times as clinically warranted. FSBG values were recorded from the medical record (CPRS) and compared to Libre values downloaded to LibreView. The mean absolute relative difference (MARD) between FSBG and Libre was calculated for each patient for one to three days. The average MARD across all patients was calculated. Accuracy was further assessed using the Bland-Altman Plot and error grid analysis using web-based tool. Of the 21 patients assessed in the validation phase, 19 had at least one day of data and 11 had at least three days. The mean MARD was 11.2% after one day, and 12.5% after three days. Four patients after one day and three patients after three days had a MARD of 15–20% where use of the Libre was continued with confirmatory FSBG. In 15/19 (78%) patients with one day of data and 8/11 (73%) of patients with 3 days of data had a MARD <15% and continued using the Libre without further FSBG. One patient had a MARD >20% that did not improve with changing the sensor, and Libre was discontinued. In 16 of 19 patients, the Libre values were lower than FSBG. No adverse events relating to Libre use were identified. Error grid analysis showed that most patients had no values outside the A and B ranges, and very few values outside of the clinically accurate range, occurring in 2 of the 19 patients (9% of values in the “slight risk” zone in 9% in one and 6% in the other). The Libre was well-accepted by patient and nursing staff, but did not have measurable effect on glycemic control, hypoglycemic events, or hospitalization measures. The libre was deemed a useful intervention in inpatients, but it can be inaccurate or only moderately accurate compared to FSBG in enough patients to require checking accuracy for at least 1–3 days. Inaccurate Libre values were mostly lower than FSBG requiring confirmatory measures of low Libre values with FSBG in our experience.

Association of Baseline Characteristics With Insulin Sensitivity and β-Cell Function in the Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) Study Cohort

OBJECTIVE

We investigated sex and racial differences in insulin sensitivity, β-cell function, and glycated hemoglobin (HbA_1c) and the associations with selected phenotypic characteristics.

RESEARCH DESIGN AND METHODS

This is a cross-sectional analysis of baseline data from 3,108 GRADE (Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness Study) participants. All had type 2 diabetes diagnosed <10 years earlier and were on metformin monotherapy. Insulin sensitivity and β-cell function were evaluated using the HOMA of insulin sensitivity and estimates from oral glucose tolerance tests, including the Matsuda Index, insulinogenic index, C-peptide index, and oral disposition index (DI).

RESULTS

The cohort was 56.6 ± 10 years of age (mean ± SD), 63.8% male, with BMI 34.2 ± 6.7 kg/m², HbA_1c 7.5 ± 0.5%, and type 2 diabetes duration 4.0 ± 2.8 years. Women had higher DI than men but similar insulin sensitivity. DI was the highest in Black/African Americans, followed by American Indians/Alaska Natives, Asians, and Whites in descending order. Compared with Whites, American Indians/Alaska Natives had significantly higher HbA_1c, but Black/African Americans and Asians had lower HbA_1c. However, when adjusted for glucose levels, Black/African Americans had higher HbA_1c than Whites. Insulin sensitivity correlated inversely with BMI, waist-to-hip ratio, triglyceride-to-HDL-cholesterol ratio (TG/HDL-C), and the presence of metabolic syndrome, whereas DI was associated directly with age and inversely with BMI, HbA_1c, and TG/HDL-C.

CONCLUSIONS

In the GRADE cohort, β-cell function differed by sex and race and was associated with the concurrent level of HbA_1c. HbA_1c also differed among the races, but not by sex. Age, BMI, and TG/HDL-C were associated with multiple measures of β-cell function and insulin sensitivity.

In older adults with type 1 diabetes, continuous glucose monitoring reduced hypoglycemia over 6 months

Pratley RE, Kanapka LG, Rickels MR, et al. Effect of continuous glucose monitoring on hypoglycemia in older adults with type 1 diabetes: a randomized clinical trial. JAMA. 2020;323:2397-406. 32543682.

Novel Detection and Restorative Levodopa Treatment for Preclinical Diabetic Retinopathy

Diabetic retinopathy (DR) is diagnosed clinically by directly viewing retinal vascular changes during ophthalmoscopy or through fundus photographs. However, electroretinography (ERG) studies in humans and rodents have revealed that retinal dysfunction is demonstrable prior to the development of visible vascular defects. Specifically, delays in dark-adapted ERG oscillatory potential (OP) implicit times in response to dim-flash stimuli (<-1.8 log cd · s/m²) occur prior to clinically recognized DR. Animal studies suggest that retinal dopamine deficiency underlies these early functional deficits. In this study, we randomized individuals with diabetes, without clinically detectable retinopathy, to treatment with either low- or high-dose Sinemet (levodopa plus carbidopa) for 2 weeks and compared their ERG findings with those of control subjects (no diabetes). We assessed dim-flash-stimulated OP delays using a novel handheld ERG system (RETeval) at baseline and 2 and 4 weeks. RETeval recordings identified significant OP implicit time delays in individuals with diabetes without retinopathy compared with age-matched control subjects (P < 0.001). After 2 weeks of Sinemet treatment, OP implicit times were restored to control values, and these improvements persisted even after a 2-week washout. We conclude that detection of dim-flash OP delays could provide early detection of DR and that Sinemet treatment may reverse retinal dysfunction.

Implementation of Continuous Glucose Monitoring in the Hospital: Emergent Considerations for Remote Glucose Monitoring During the COVID-19 Pandemic

Continuous glucose monitoring (CGM) has become a widely used tool in the ambulatory setting for monitoring glucose levels, as well as detecting uncontrolled hyperglycemia, hypoglycemia, and glycemic variability. The accuracy of some CGM systems has recently improved to the point of manufacture with factory calibration and Food and Drug Administration clearance for nonadjunctive use to dose insulin. In this commentary, we analyze the answers to six questions about what is needed to bring CGM into the hospital as a reliable, safe, and effective tool. The evidence to date indicates that CGM offers promise as an effective tool for monitoring hospitalized patients. During the current coronavirus disease 2019 crisis, we hope to provide guidance to healthcare professionals, who are seeking to reduce exposure to SARS-Cov-2, as well as preserve invaluable personal protective equipment. In this commentary, we address who, what, where, when, why, and how CGM can be adopted for inpatient use.

Global status of diabetes prevention and prospects for action: A consensus statement

Primary prevention of type 2 diabetes (T2D) should be achievable through the implementation of early and sustainable measures. Several randomized control studies that found success in preventing the progression to T2D in high-risk populations have identified early and intensive intervention based on an individualized prevention model as the key factor for participant benefit. The global prevalence of both overweight and obesity has now been widely recognized as the major epidemic of the 21st century. Obesity is a major risk factor for the progression from normal glucose tolerance to prediabetes and then to T2D. However, not all obese individuals will develop prediabetes or progress to diabetes. Intensive, multicomponent behavioural interventions for overweight and obese adults can lead to weight loss. Diabetes medications, including metformin, GLP-1 agonists, glitazones, and acarbose, can be considered for selected high-risk patients with prediabetes when lifestyle-based programmes are proven unsuccessful. Nutrition education is the cornerstone of a healthy lifestyle. Also, physical activity is an integral part of the prediabetes management plan and one of the main pillars in the prevention of diabetes. Mobile phones, used extensively worldwide, can facilitate communication between health professionals and the general population, and have been shown to be helpful in the prevention of T2D. Universal screening is needed. Noninvasive risk scores should be used in all countries, but they should be locally validated in all ethnic populations focusing on cultural differences around the world. Lifestyle interventions reduce the progression to prediabetes and diabetes. Nevertheless, many questions still need to be answered.

Dopamine Deficiency Mediates Early Rod-Driven Inner Retinal Dysfunction in Diabetic Mice

Purpose

Electroretinograms (ERGs) are abnormal in diabetic retinas before the appearance of vascular lesions, providing a possible biomarker for diabetic vision loss. Previously, we reported that decreased retinal dopamine (DA) levels in diabetic rodents contributed to early visual and retinal dysfunction. In the current study, we examined whether oscillatory potentials (OPs) could serve as a potential marker for detecting early inner retinal dysfunction due to retinal DA deficiency.

Methods

Retinal function was tested with dark-adapted ERGs, taken at 3, 4, and 5 weeks after diabetes induction with streptozotocin. Electrical responses were analyzed and correlations were made with previously reported retinal DA levels. The effect of restoring systemic DA levels or removing DA from the retina in diabetic mice on OPs was assessed using L-3,4-dihydroxyphenylalanine (L-DOPA) treatments and retina-specific tyrosine hydroxylase (Th) knockout mice (rTHKO), respectively.

Results

Diabetic animals had significantly delayed OPs compared to control animals in response to dim, but not bright, flash stimuli. L-DOPA treatment preserved OP implicit time in diabetic mice. Diabetic rTHKO mice had further delayed OPs compared to diabetic mice with normal retinal Th, with L-DOPA treatment also providing benefit. Decreasing retinal DA levels significantly correlated with increasing OP delays mediated by rod pathways.

Conclusions

Our data suggest that inner retinal dysfunction in early-stage diabetes is mediated by rod-pathway deficits and DA deficiencies. OP delays may be used to determine the earliest functional deficits in diabetic retinopathy and to establish an early treatment window for DA therapies that may prevent progressive vision loss.

Inpatient Glucose Values: Determining the Nondiabetic Range and Use in Identifying Patients at High Risk for Diabetes

BACKGROUND

Many individuals with diabetes remain undiagnosed, leading to delays in treatment and higher risk for subsequent diabetes complications. Despite recommendations for diabetes screening in high-risk groups, the optimal approach is not known. We evaluated the utility of inpatient glucose levels as an opportunistic screening tool for identifying patients at high risk for diabetes.

METHODS

We retrospectively examined 462,421 patients in the US Department of Veterans Affairs healthcare system, hospitalized on medical/surgical services in 2000-2010, for ≥3 days, with ≥2 inpatient random plasma glucose (RPG) measurements. All had continuity of care: ≥1 primary care visit and ≥1 glucose measurement within 2 years before hospitalization and yearly for ≥3 years after discharge. Glucose levels during hospitalization and incidence of diabetes within 3 years after discharge in patients without diabetes were evaluated.

RESULTS

Patients had a mean age of 65.0 years, body mass index of 29.9 kg/m², and were 96% male, 71% white, and 18% black. Pre-existing diabetes was present in 39.4%, 1.3% were diagnosed during hospitalization, 8.1% were diagnosed 5 years after discharge, and 51.3% were never diagnosed (NonDM). The NonDM group had the lowest mean hospital RPG value (112 mg/dL [6.2 mmol/L]). Having at least 2 RPG values >140 mg/dL (>7.8 mmol/L), the 95th percentile of NonDM hospital glucose, provided 81% specificity for identifying incident diabetes within 3 years after discharge.

CONCLUSIONS

Screening for diabetes could be considered in patients with at least 2 hospital glucose values at/above the 95th percentile of the nondiabetic range (141 mg/dL [7.8 mmol/L]).

A Randomized Controlled Study Comparing a DPP4 Inhibitor (Linagliptin) and Basal Insulin (Glargine) in Patients With Type 2 Diabetes in Long-term Care and Skilled Nursing Facilities: Linagliptin-LTC Trial

OBJECTIVES

Safe and easily implemented treatment regimens are needed for the management of patients with type 2 diabetes mellitus (T2DM) in long-term care (LTC) and skilled nursing facilities.

DESIGN

This 6-month open-label randomized controlled trial compared the efficacy and safety of a DPP4 inhibitor (linagliptin) and basal insulin (glargine) in LTC residents with T2DM.

SETTINGS

Three LTC institutions affiliated with a community safety-net hospital, US Department of Veterans Affairs and Emory Healthcare System in Atlanta, Georgia.

PARTICIPANTS

A total of 140 residents with T2DM treated with oral antidiabetic agents or low-dose insulin (≤0.1 U/kg/d), with fasting or premeal blood glucose (BG) > 180 mg/dL and/or HbA1c >7.5%.

INTERVENTION

Baseline antidiabetic therapy, except metformin, was discontinued on trial entry. Residents were treated with linagliptin 5 mg/d (n = 67) or glargine at a starting dose of 0.1 U/kg/d (n = 73). Both groups received supplemental rapid-acting insulin before meals for BG > 200 mg/dL.

MEASUREMENTS

Primary outcome was mean difference in daily BG between groups. Main secondary endpoints included differences in frequency of hypoglycemia, glycosylated hemoglobin (HbA1c), complications, emergency department visits, and hospital transfers.

RESULTS

Treatment with linagliptin resulted in no significant differences in mean daily BG (146 ± 34 mg/dL vs. 157 ± 36 mg/dL, P = .07) compared to glargine. Linagliptin treatment resulted in fewer mild hypoglycemic events <70 mg/dL (3% vs. 37%, P < .001), but there were no differences in BG < 54 mg/dL (P = .06) or <40 mg/dL (P = .05) compared to glargine. There were no significant between-group differences in HbA1c, length of stay, complications, emergency department visits, or hospitalizations.

CONCLUSION

Treatment with linagliptin resulted in noninferior glycemic control and in significantly lower risk of hypoglycemia compared to insulin glargine in long-term care and skilled nursing facility residents with type 2 diabetes.

Participation in a National Lifestyle Change Program is associated with improved diabetes Control outcomes

AIMS

Clinical trials show lifestyle change programs are beneficial, yet large-scale, successful translation of these programs is scarce. We investigated the association between participation in the largest U.S. lifestyle change program, MOVE!, and diabetes control outcomes.

METHODS

This longitudinal, retrospective cohort study used Veterans Health Administration databases of patients with diabetes who participated in MOVE! between 2005 and 2012, or met eligibility criteria (BMI ≥25kg/m²) but did not participate. Main outcomes were diabetic eye disease, renal disease, and medication intensification.

RESULTS

There were 400,170 eligible patients with diabetes, including 87,366 (22%) MOVE!

PARTICIPANTS

Included patients were 96% male, 77% white, with mean age 58years and BMI 34kg/m². Controlling for baseline measurements and age, race, sex, BMI, and antidiabetes medications, MOVE! participants had lower body weight (-0.6kg), random plasma glucose (-2.8mg/dL), and HbA1c (-0.1%) at 12months compared to nonparticipants (each p<0.001). In multivariable Cox models, MOVE! participants had lower incidence of eye disease (hazard ratio 0.80, 95% CI 0.75-0.84) and renal disease (HR 0.89, 95% CI 0.86-0.92) and reduced medication intensification (HR 0.82, 95% CI 0.80-0.84).

CONCLUSIONS

If able to overcome participation challenges, lifestyle change programs in U.S. health systems may improve health among the growing patient population with diabetes.

Glucose challenge test screening for prediabetes and early diabetes

AIMS

To test the hypothesis that a 50-g oral glucose challenge test with 1-h glucose measurement would have superior performance compared with other opportunistic screening methods.

METHODS

In this prospective study in a Veterans Health Administration primary care clinic, the following test performances, measured by area under receiver-operating characteristic curves, were compared: 50-g oral glucose challenge test; random glucose; and HbA_1c level, using a 75-g oral glucose tolerance test as the 'gold standard'.

RESULTS

The study population was comprised of 1535 people (mean age 56 years, BMI 30.3 kg/m² , 94% men, 74% black). By oral glucose tolerance test criteria, diabetes was present in 10% and high-risk prediabetes was present in 22% of participants. The plasma glucose challenge test provided area under receiver-operating characteristic curves of 0.85 (95% CI 0.78-0.91) to detect diabetes and 0.76 (95% CI 0.72-0.80) to detect high-risk dysglycaemia (diabetes or high-risk prediabetes), while area under receiver-operating characteristic curves for the capillary glucose challenge test were 0.82 (95% CI 0.75-0.89) and 0.73 (95% CI 0.69-0.77) for diabetes and high-risk dysglycaemia, respectively. Random glucose performed less well [plasma: 0.76 (95% CI 0.69-0.82) and 0.66 (95% CI 0.62-0.71), respectively; capillary: 0.72 (95% CI 0.65-0.80) and 0.64 (95% CI 0.59-0.68), respectively], and HbA_1c performed even less well [0.67 (95% CI 0.57-0.76) and 0.63 (95% CI 0.58-0.68), respectively]. The cost of identifying one case of high-risk dysglycaemia with a plasma glucose challenge test would be $42 from a Veterans Health Administration perspective, and $55 from a US Medicare perspective.

CONCLUSIONS

Glucose challenge test screening, followed, if abnormal, by an oral glucose tolerance test, would be convenient and more accurate than other opportunistic tests. Use of glucose challenge test screening could improve management by permitting earlier therapy.

mRNA destabilization improves glycemic responsiveness of transcriptionally regulated hepatic insulin gene therapy in vitro and in vivo

BACKGROUND

Hepatic insulin gene therapy (HIGT) employing a glucose and insulin sensitive promoter to direct insulin transcription can lower blood sugars within 2 h of an intraperitoneal glucose challenge. However, post-challenge blood sugars frequently decline to below baseline. We hypothesize that this 'over-shoot' hypoglycemia results from sustained translation of long-lived transgene message, and that reducing pro-insulin message half-life will ameliorate post-challenge hypoglycemia.

METHODS

We compared pro-insulin message content and insulin secretion from primary rat hepatocytes expressing insulin from either a standard construct (2xfur), or a construct producing a destabilized pro-insulin message (InsTail), following exposure to stimulating or inhibitory conditions.

RESULTS

Hepatocytes transduced with a 2xfur construct accumulated pro-insulin message, and exhibited increased insulin secretion, under conditions that both inhibit or stimulate transcription. By contrast, pro-insulin message content remained stable in InsTail expressing cells, and insulin secretion increased less than 2xfur during prolonged stimulation. During transitions from stimulatory to inhibitory conditions, or vice versa, amounts of pro-insulin message changed more rapidly in InsTail expressing cells than 2xfur expressing cells. Importantly, insulin secretion increased during the transition from stimulation to inhibition in 2xfur expressing cells, although it remained unchanged in InsTail expressing cells. Use of the InsTail destabilized insulin message tended to more rapidly reduce glucose induced glycemic excursions, and limit post-load hypoglycemia in STZ-diabetic mice in vivo.

CONCLUSIONS

The data obtained in the present study suggest that combining transcriptional and post-transcriptional regulatory strategies may reduce undesirable glycemic excursion in models of HIGT.

Long-term glycemic control with hepatic insulin gene therapy in streptozotocin-diabetic mice

BACKGROUND

Insulin self-administration is burdensome and can produce dangerous hypoglycemia. Insulin gene therapy may improve and simplify the treatment of diabetes mellitus. In rats, metabolically responsive hepatic insulin gene therapy (HIGT) delivered by adenovirus normalizes random blood sugars but with a limited duration. To prolong glycemic control, we delivered a metabolically regulated insulin transgene by adeno-associated virus (AAV).

METHODS

We administered increasing doses of self-complementary (SC), pseudotyped AAV8 expressing the (GlRE)3 BP1-2xfur insulin transgene to streptozotocin-diabetic CD-1 mice, and monitored blood sugar and body weight. We also compared responses to intraperitoneal glucose and chow withdrawal, assessed for viral genomes in liver by Southern blotting, and measured hepatic glycogen.

RESULTS

Glucose lowering required the combination of SC genomes and AAV capsid pseudotyping. HIGT controlled glycemia in diabetic mice (DM) for > 1 year. However, glycemic responses were variable. Approximately 30% of mice succumbed to hypoglycemia, and approximately 30% of mice again became hyperglycemic. During an intraperitoneal glucose tolerance test, blood sugars declined to normal within 180 min in HIGT-treated DM compared to 90 min in control mice. Hypoglycemia was common among HIGT-treated mice during a 24-h fast. However, HIGT mice lost less weight than either diabetic or nondiabetic controls as a result of increased water intake. HIGT treatment reduced the hepatic glycogen content of fed mice.

CONCLUSIONS

Our studies demonstrate the possibility for long-term glycemic correction following AAV-mediated HIGT in mice. However, the dose-response relationship is irregular, and metabolic responsiveness may be less than that observed in rats.

Translating What Works: A New Approach to Improve Diabetes Management

BACKGROUND

The most efficacious strategies to improve diabetes control include case management, health care team changes, patient education, and facilitated transmission of patient data to clinicians ("facilitated relay"), but these strategies have not been translated to permit general use in clinical practice.

METHODS

A web-based decision support program was developed to include these features, and assessed in patients who had A1c ≥7.0% despite using metformin with/without sulfonylureas or insulin. Staff entered patients' glucose data, obtained management recommendations, reviewed the plan with a clinician, and discussed the new plan with patients.

RESULTS

113 subjects were 96% male and 32% black, with average age 65.6 years and BMI 32.8. During prior primary care, A1c averaged 8.32 ± 0.16% (SEM). In all patients, baseline A1c was 8.18 ± 0.11%, and decreased to 7.54 ± 0.12%, 7.16 ± 0.13%, and 7.54 ± 0.16% at 3, 6, and 12 months, respectively, all P < .001. In 42 subjects who provided glucose data and made requested changes in medications, A1c was 8.12 ± 0.09% at baseline and fell to 7.29 ± 0.11%, 6.98 ± 0.10%, and 7.05 ± 0.10% at 3, 6, and 12 months, respectively, all P < .001. Chart review of 16 subjects followed for 12 months demonstrated that hypoglycemia (symptoms and/or glucose <70 mg/dl) averaged less than 1 episode/patient/month, and there was no severe hypoglycemia.

CONCLUSIONS

A novel decision support program improved A1c with little hypoglycemia. Use of this approach should allow primary care teams to keep patients well controlled, and reduce the need for specialist referrals.

Increased cardiovascular disease, resource use, and costs before the clinical diagnosis of diabetes in veterans in the southeastern U.S

IMPORTANCE

Screening for diabetes might be more widespread if adverse associations with cardiovascular disease (CVD), resource use, and costs were known to occur earlier than conventional clinical diagnosis.

OBJECTIVE

The purpose of this study was to determine whether adverse effects associated with diabetes begin prior to clinical diagnosis.

DESIGN

Veterans with diabetes were matched 1:2 with controls by follow-up, age, race/ethnicity, gender, and VA facility. CVD was obtained from ICD-9 codes, and resource use and costs from VA datasets.

SETTING

VA facilities in SC, GA, and AL.

PARTICIPANTS

Patients with and without diagnosed diabetes.

MAIN OUTCOME MEASURES

Diagnosed CVD, resource use, and costs.

RESULTS

In this study, the 2,062 diabetic patients and 4,124 controls were 63 years old on average, 99 % male, and 29 % black; BMI was 30.8 in diabetic patients vs. 27.8 in controls (p<0.001). CVD prevalence was higher and there were more outpatient visits in Year -4 before diagnosis through Year +4 after diagnosis among diabetic vs. control patients (all p<0.01); in Year -2, CVD prevalence was 31 % vs. 24 %, and outpatient visits were 22 vs. 19 per year, respectively. Total VA costs/year/veteran were higher in diabetic than control patients from Year -4 ($4,083 vs. $2,754) through Year +5 ($8,347 vs. $5,700) (p<0.003) for each, reflecting underlying increases in outpatient, inpatient, and pharmacy costs (p<0.05 for each). Regression analysis showed that diabetes contributed an average of $1,748/year to costs, independent of CVD (p<0.001).

CONCLUSIONS AND RELEVANCE

VA costs per veteran are higher--over $1,000/year before and $2,000/year after diagnosis of diabetes--due to underlying increases in outpatient, inpatient, and pharmacy costs, greater number of outpatient visits, and increased CVD. Moreover, adverse associations with veterans' health and the VA healthcare system occur early in the natural history of the disease, several years before diabetes is diagnosed. Since adverse associations begin before diabetes is recognized, greater consideration should be given to systematic screening in order to permit earlier detection and initiation of preventive management. Keeping frequency of CVD and marginal costs in line with those of patients before diabetes is currently diagnosed has the potential to save up to $2 billion a year.

Weight loss and incidence of diabetes with the Veterans Health Administration MOVE! lifestyle change programme: an observational study

BACKGROUND

Programmes for lifestyle change are aimed at improving health but little is known about their effectiveness in clinical settings. The Veterans Health Administration (VA) MOVE! lifestyle change programme is the largest in the USA. We investigated whether participation in MOVE! is associated with reduced incidence of diabetes.

METHODS

We did a retrospective observational analysis of data from VA databases in overweight patients and obese patients with a weight-related disorder who had undergone at least 3 years of continuous outpatient care in 2005-12. We used generalised estimating equations to assess characteristics associated with MOVE! participation, and Cox's proportional hazards regression to analyse the association between participation and diabetes incidence.

FINDINGS

Of 1·8 million eligible individuals, 238 540 (13%) participated in the MOVE! programme. 19 367 (1% overall, 8% of participants) met criteria for intense and sustained participation (at least eight sessions within 6 months over at least a 4-month span), which was associated with greater weight loss at 3 years than low-intensity or no participation (-2·2% vs -0·64% or 0·46%). Compared with non-participation, incidence of diabetes was reduced by intense and sustained participation (hazard ratio 0·67, 95% CI 0·61-0·74) and low-intensity participation (0·80, 0·77-0·83) in MOVE!. These patterns were consistent across sex, ethnic origin, and age. Participation was most beneficial in patients with high BMI or high random glucose concentrations at baseline (both pinteraction<0·0001).

INTERPRETATION

Participation in the MOVE! programme was associated with weight loss and reduced incidence of diabetes, but the rate of participation was low and, therefore, selection bias could have exaggerated these effects.

FUNDING

US Department of Veterans Affairs, National Institutes of Health.

Hospital discharge algorithm based on admission HbA1c for the management of patients with type 2 diabetes

OBJECTIVE

Effective treatment algorithms are needed to guide diabetes care at hospital discharge in general medicine and surgery patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This was a prospective, multicenter open-label study aimed to determine the safety and efficacy of a hospital discharge algorithm based on admission HbA1c. Patients with HbA1c <7% (53.0 mmol/mol) were discharged on their preadmission diabetes therapy, HbA1c between 7 and 9% (53.0-74.9 mmol/mol) were discharged on a preadmission regimen plus glargine at 50% of hospital daily dose, and HbA1c >9% were discharged on oral antidiabetes agents (OADs) plus glargine or basal bolus regimen at 80% of inpatient dose. The primary outcome was HbA1c concentration at 12 weeks after hospital discharge.

RESULTS

A total of 224 patients were discharged on OAD (36%), combination of OAD and glargine (27%), basal bolus (24%), glargine alone (9%), and diet (4%). The admission HbA1c was 8.7 ± 2.5% (71.6 mmol/mol) and decreased to 7.3 ± 1.5% (56 mmol/mol) at 12 weeks of follow-up (P < 0.001). The change of HbA1c from baseline at 12 weeks after discharge was -0.1 ± 0.6, -0.8 ± 1.0, and -3.2 ± 2.4 in patients with HbA1c <7%, 7-9%, and >9%, respectively (P < 0.001). Hypoglycemia (<70 mg/dL) was reported in 22% of patients discharged on OAD only, 30% on OAD plus glargine, 44% on basal bolus, and 25% on glargine alone and was similar in patients with admission HbA1c ≤7% (26%) compared with those with HbA1c >7% (31%, P = 0.54).

CONCLUSIONS

Measurement of HbA1c on admission is beneficial in tailoring treatment regimens at discharge in general medicine and surgery patients with type 2 diabetes.

Aging is associated with increased HbA1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA1c diagnostic specificity

AIM

To determine whether using HbA1c for screening and management could be confounded by age differences, whether age effects can be explained by unrecognized diabetes and prediabetes, insulin resistance or postprandial hyperglycaemia, and whether the effects of aging have an impact on diagnostic accuracy.

METHODS

We conducted a cross-sectional analysis in adults without known diabetes in the Screening for Impaired Glucose Tolerance (SIGT) study 2005-2008 (n=1573) and the National Health and Nutrition Examination Survey (NHANES) 2005-2006 (n=1184).

RESULTS

Both glucose intolerance and HbA(1c) levels increased with age. In univariate analyses including all subjects, HbA(1c) levels increased by 0.93 mmol/mol (0.085%) per 10 years of age in the SIGT study and by 1.03 mmol/mol (0.094%) per 10 years in the NHANES; in both datasets, the HbA(1c) increase was 0.87 mmol/mol (0.08%) per 10 years in subjects without diabetes, and 0.76 mmol/mol (0.07%) per 10 years in subjects with normal glucose tolerance, all P<0.001. In multivariate analyses of subjects with normal glucose tolerance, the relationship between age and HbA(1c) remained significant (P<0.001) after adjustment for covariates including race, BMI, waist circumference, sagittal abdominal diameter, triglyceride/HDL ratio, and fasting and 2-h plasma glucose and other glucose levels, as assessed by an oral glucose tolerance test. In both datasets, the HbA(1c) of an 80-year-old individual with normal glucose tolerance would be 3.82 mmol/mol (0.35%) greater than that of a 30-year-old with normal glucose tolerance, a difference that is clinically significant. Moreover, the specificity of HbA(1c) -based diagnostic criteria for prediabetes decreased substantially with increasing age (P<0.0001).

CONCLUSIONS

In two large datasets, using different methods to measure HbA(1c), the association of age with higher HbA(1c) levels: was consistent and similar; was both statistically and clinically significant; was unexplained by features of aging; and reduced diagnostic specificity. Age should be taken into consideration when using HbA(1c) for the diagnosis and management of diabetes and prediabetes.

Rodent Hyperglycemia-Induced Inner Retinal Deficits are Mirrored in Human Diabetes

PURPOSE

To evaluate the utility of low luminance stimuli to functionally probe inner retinal rod pathways in the context of diabetes mellitus in both rat and human subjects.

METHODS

Inner retinal dysfunction was assessed using oscillatory potential (OP) delays in diabetic rats. Scotopic electroretinograms (ERGs) in response to a series of increasing flash luminances were recorded from streptozotocin (STZ)-treated and control Sprague-Dawley rats after 7, 14, 20, and 29 weeks of hyperglycemia. We then evaluated OP delays in human diabetic subjects with (DR) and without (DM) diabetic retinopathy using the International Society for Clinical Electrophysiology in Vision (ISCEV) standard scotopic protocol and two additional dim test flashes.

RESULTS

Beginning 7 weeks after STZ, OP implicit times in diabetic rats were progressively delayed in response to dim, but not bright stimuli. In many diabetic subjects the standard ISCEV dim flash failed to illicit measureable OPs. However, OPs became measurable using a brighter, nonstandard dim flash (Test Flash 1, -1.43 log cd s/m²), and exhibited prolonged implicit times in the DM group compared with control subjects (CTRL).

CONCLUSIONS

Delays in scotopic OP implicit times are an early response to hyperglycemia in diabetic rats. A similar, inner retinal, rod-driven response was detected in diabetic human subjects without diabetic retinopathy, only when a nonstandard ISCEV flash intensity was employed during ERG testing.

TRANSLATIONAL RELEVANCE

The addition of a dim stimulus to standard ISCEV flashes with assessment of OP latency during ERG testing may provide a detection method for early retinal dysfunction in diabetic patients.

Differences in inpatient glycemic control and response to subcutaneous insulin therapy between medicine and surgery patients with type 2 diabetes

OBJECTIVE

To determine differences in inpatient glycemic control and response to two different glargine-based insulin regimens in general medicine and surgery patients with type 2 diabetes (T2D).

METHODS

This is a post-hoc analysis of a prospective, multicenter, randomized trial of 298 non-ICU medicine and surgery patients with T2D treated with Basal Bolus regimen with glargine once daily and glulisine before meals and with Basal Plus regimen with glargine once daily and supplemental doses of glulisine before meals for blood glucose (BG)>140mg/dl. Major study outcomes included differences in mean daily BG, frequency of treatment failures (defined as >2 consecutive BG>240mg/dl or a mean daily BG>240mg/dl), and hypoglycemia between the medicine and surgery cohorts.

RESULTS

Patients treated with Basal Bolus or with Basal Plus experienced similar improvement in mean daily BG after 1st day of therapy (p=0.16), number of treatment failures (p=0.11) and hypoglycemic events (p=0.50). Compared to surgery patients (n=130), medicine patients (n=168) had higher admission BG (p=0.01) and HbA1c levels (p<0.01); however, they had similar response to either treatment regimen without differences in mean daily BG after 1st day of therapy (p=0.18), number of treatment failures (p=0.58), daily insulin requirements (p=0.36), or in the frequency of hypoglycemia (p=0.79).

CONCLUSION

The Basal Plus regimen with glargine once daily and correction doses with glulisine before meals resulted in similar glycemic control to basal bolus regimen. We observed no differences in response to either basal insulin regimen between medicine and surgery patients with type 2 diabetes.

Randomized study comparing a Basal-bolus with a basal plus correction insulin regimen for the hospital management of medical and surgical patients with type 2 diabetes: basal plus trial

OBJECTIVE

Effective and easily implemented insulin regimens are needed to facilitate hospital glycemic control in general medical and surgical patients with type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

This multicenter trial randomized 375 patients with T2D treated with diet, oral antidiabetic agents, or low-dose insulin (≤ 0.4 units/kg/day) to receive a basal-bolus regimen with glargine once daily and glulisine before meals, a basal plus regimen with glargine once daily and supplemental doses of glulisine, and sliding scale regular insulin (SSI).

RESULTS

Improvement in mean daily blood glucose (BG) after the first day of therapy was similar between basal-bolus and basal plus groups (P = 0.16), and both regimens resulted in a lower mean daily BG than did SSI (P = 0.04). In addition, treatment with basal-bolus and basal plus regimens resulted in less treatment failure (defined as >2 consecutive BG >240 mg/dL or a mean daily BG >240 mg/dL) than did treatment with SSI (0 vs. 2 vs. 19%, respectively; P < 0.001). A BG <70 mg/dL occurred in 16% of patients in the basal-bolus group, 13% in the basal plus group, and 3% in the SSI group (P = 0.02). There was no difference among the groups in the frequency of severe hypoglycemia (<40 mg/dL; P = 0.76).

CONCLUSIONS

The use of a basal plus regimen with glargine once daily plus corrective doses with glulisine insulin before meals resulted in glycemic control similar to a standard basal-bolus regimen. The basal plus approach is an effective alternative to the use of a basal-bolus regimen in general medical and surgical patients with T2D.

Early visual deficits in streptozotocin-induced diabetic long evans rats

PURPOSE

Although diabetic retinopathy (DR) is clinically diagnosed based on vascular pathology, diabetic patients with angiographically normal retinas have been found to exhibit subtle defects in vision. This has led to the theory that diabetes-associated metabolic abnormalities directly impair neural retinal function before the development of vasculopathy, thereby resulting in visual deficits. In this study, we sought to delineate the temporal relationship between retinal dysfunction and visual deficits in a rat model of Type 1 diabetes. Moreover, we investigated the relative contribution of retinal dysfunction versus diabetes-induced lens opacity, to the visual deficits found in early-stage DR.

METHODS

Pigmented Long Evans rats were rendered diabetic with streptozotocin (STZ). Control and diabetic rats were assessed across 12 weeks of hyperglycemia for visual function with optokinetic tracking weekly visual acuity and monthly contrast sensitivity, retinal function with dark-adapted electroretinograms (monthly electroretinograms [ERGs]), and cataract formation with slit lamp exam (biweekly).

RESULTS

Diabetic rats exhibited significantly reduced visual function and delayed ERG responses by 1 month post-STZ. Significant cataracts did not develop until 6 weeks post-STZ. Moreover, increases in lens opacity (r = -0.728) and ERG implicit times (r = -0.615 for rod-dominated response and r = -0.322 for rod/cone mixed response) showed significant correlations with reductions in visual acuity in diabetic rats.

CONCLUSIONS

STZ-induced hyperglycemia reduces visual function, affecting both visual acuity and contrast sensitivity. The data suggest that visual defects found in early-stage DR may initially involve abnormalities of the neural retina and worsen with later development of cataracts.

[Effects of hepatic insulin gene therapy on enteric neuropathy in STZ-diabetic mice]

OBJECTIVE

To evaluate the effect of hepatic insulin gene therapy on diabetic enteric neuropathy.

METHODS

Mice were randomly allocated into 3 groups: a normal control group, a diabetic group, and a diabetic gene therapy group. Diabetes were induced by penial vein injection of streptozocin (STZ). The gene therapy group received hepatic insulin gene therapy while the other 2 groups only received an empty virus expressing green fluorescent protein. Random blood glucose, body weight growth, gastric emptying, total bowel length, absolute and relative bowel transit, electric field stimulation of colon smooth muscle, colon nuclei staining and counting were measured.

RESULTS

We successully established a mouse model of diabetic enteric neuropathy which manifests as: 8 weeks of continuous hyperglycemia,increased total bowel length, decreased relative bowel transit, impaired colon smooth muscle relaxation and loss of inhibitory neurons in colon. Through gene therapy, the above indexes were normalized or ameliorated, suggesting hepatic insulin gene therapy is capable of preventing diabetic enteric neuropathy.

CONCLUSION

Hepatic insulin gene therapy can prevent STZ induced diabetic enteric neuropathy.

Effect of macronutrients, age, and obesity on 6- and 24-h postprandial glucose metabolism in cats

Obesity and age are risk factors for feline diabetes. This study aimed to test the hypothesis that age, long-term obesity, and dietary composition would lead to peripheral and hepatorenal insulin resistance, indicated by higher endogenous glucose production (EGP) in the fasted and postprandial state, higher blood glucose and insulin, and higher leptin, free thyroxine, and lower adiponectin concentrations. Using triple tracer-(2)H(2)O, [U-(13)C(3)] propionate, and [3,4-(13)C(2)] glucose infusion, and indirect calorimetry-we investigated carbohydrate and fat metabolic pathways in overnight-fasted neutered cats (13 young lean, 12 old lean, and 12 old obese), each fed three different diets (high protein with and without polyunsaturated fatty acids, and high carbohydrate) in a crossover design. EGP was lowest in fasted and postprandial obese cats despite peripheral insulin resistance, indicated by hyperinsulinemia. Gluconeogenesis was the most important pathway for EGP in all groups, but glycogen contributed significantly. Insulin and leptin concentrations were higher in old than in young lean cats; adiponectin was lowest in obese cats but surprisingly highest in lean old cats. Diet had little effect on metabolic parameters. We conclude that hepatorenal insulin resistance does not develop in the fasted or postprandial state, even in long-term obese cats, allowing the maintenance of euglycemia through lowering EGP. Glycogen plays a major role in EGP, especially in lean fasted cats, and in the postprandial state. Aging may predispose to insulin resistance, which is a risk factor for diabetes in cats. Mechanisms underlying the high adiponectin of healthy old lean cats need to be further explored.

Validity of the primary care diagnosis of diabetes in veterans in the southeastern United States

AIMS

To determine the validity of diagnosis of diabetes in primary care.

METHODS

Patients with initial primary care diagnosis (ICD-9 code 250.xx) were compared to matched controls (without code or diabetes drugs), and patients meeting VA Diabetes Epidemiology Cohort (DEpiC) criteria (any 250.xx twice, or diabetes drug) in "diagnostic accuracy" (whether hyperglycemia preceded diagnosis) and "predictive accuracy" (whether diabetes drug or A1c ≥ 6.5% followed diagnosis).

RESULTS

Only 1.8% of primary care diagnoses met ADA criteria, while nonstandard non-fasting morning glucose ≥ 126 mg/dl or A1c ≥ 6.5% were utilized in 51.5%; broad "diagnostic accuracy" criteria were met in 53% of 2980 primary care vs. 2% of 13,397 control (p<0.001), and 60% of 2456 DEpiC patients (p<0.001). "Predictive accuracy" was 88% in primary care diagnosis vs. 12% control (p<0.001) and 93% DEpiC patients (p=0.08), but was higher if ADA criteria were met. Delay from hyperglycemia to diagnosis averaged 12.5 months in primary care vs. 20.1 months in DEpiC patients (p<0.001).

CONCLUSIONS

While generally not based on ADA criteria, the primary care diagnosis of diabetes is valid, and identifies patients earlier than detection by DEpiC criteria. Either primary care diagnosis or DEpiC criteria could be used to trigger electronic reminders aimed to facilitate management.

Screening for diabetes and pre-diabetes with proposed A1C-based diagnostic criteria

OBJECTIVE

An International Expert Committee (IEC) and the American Diabetes Association (ADA) proposed diagnostic criteria for diabetes and pre-diabetes based on A1C levels. We hypothesized that screening for diabetes and pre-diabetes with A1C measurements would differ from using oral glucose tolerance tests (OGTT).

RESEARCH DESIGN AND METHODS

We compared pre-diabetes, dysglycemia (diabetes or pre-diabetes), and diabetes identified by the proposed criteria (A1C ≥ 6.5% for diabetes and 6.0-6.4% [IEC] or 5.7-6.4% [ADA] for high risk/pre-diabetes) with standard OGTT diagnoses in three datasets. Non-Hispanic white or black adults without known diabetes who had A1C and 75-g OGTT measurements were included from the prospective Screening for Impaired Glucose Tolerance study (n = 1,581), and from the National Health and Nutrition Examination Survey (NHANES) III (n = 2014), and NHANES 2005-2006 (n = 1,111).

RESULTS

OGTTs revealed pre-diabetes in 35.8% and diabetes in 5.2% of combined study subjects. A1C provided receiver operating characteristic (ROC) curve areas for diabetes of 0.79-0.83, but ROC curve areas were ≤ 0.70 for dysglycemia or pre-diabetes. The proposed criteria missed 70% of individuals with diabetes, 71-84% with dysglycemia, and 82-94% with pre-diabetes. Compared with the IEC criteria, the ADA criteria for pre-diabetes resulted in fewer false-negative and more false-positive result. There were also racial differences, with false-positive results being more common in black subjects and false-negative results being more common in white subjects. With use of NHANES 2005-2006 data, ∼5.9 million non-Hispanic U.S. adults with unrecognized diabetes and 43-52 million with pre-diabetes would be missed by screening with A1C. CONCLUSIONS The proposed A1C diagnostic criteria are insensitive and racially discrepant for screening, missing most Americans with undiagnosed diabetes and pre-diabetes.

MRI reveals differential regulation of retinal and choroidal blood volumes in rat retina

The retina is nourished by two unique (retinal and choroidal) circulations. The lack of depth-resolved blood volume (BV) imaging techniques hampers investigation of vascular-specific regulation of the retina in vivo. This study presents a high-resolution, laminar-specific magnetic resonance imaging (MRI) study to image retinal and choroidal BVs, their responses to physiologic challenges in normal and Royal-College-of-Surgeons (RCS) rats (a model of retinal degeneration). Retinal and choroidal BVs were imaged by MRI (30×30×800 μm) with intravascular administration of monocrystalline iron oxide nanocolloid (MION) contrast agent. Relative baseline BV and BV changes due to physiologic challenges were calculated in normal and RCS rat retinas. BV-MRI revealed two well-resolved retinal and choroidal vascular layers located on either side of the retina and an intervening avascular layer. The ratio of choroidal:retinal BV in normal rats at baseline was 9.8±3.2 in control rat retinas (N=7). Hyperoxia decreased retinal BV (-51±17%, p<0.05) more than choroidal BV (-28±14%), and hypercapnia increased retinal BV (52±11%, p<0.01) more than choroidal BV (12±11%). BV-MRI in degenerated retinas of RCS rats (N=7) revealed thinning of the avascular layer and an increase in relative baseline retinal and choroidal BVs. Only hypercapnia-induced BV changes in the retinal vasculature of RCS rats were significantly different (smaller) from controls (p<0.05). These findings suggest that BV in both retinal vasculatures is regulated. The relative baseline BV in both vasculatures increased in retinal degeneration. BV-MRI provides clinically relevant data that may prove useful for early detection and longitudinal probing of retinal diseases, and could complement optical imaging techniques.

The impact of obesity, sex, and diet on hepatic glucose production in cats

Obesity is a risk factor for type 2 diabetes in cats. The risk of developing diabetes is severalfold greater for male cats than for females, even after having been neutered early in life. The purpose of this study was to investigate the role of different metabolic pathways in the regulation of endogenous glucose production (EGP) during the fasted state considering these risk factors. A triple tracer protocol using (2)H(2)O, [U-(13)C(3)]propionate, and [3,4-(13)C(2)]glucose was applied in overnight-fasted cats (12 lean and 12 obese; equal sex distribution) fed three different diets. Compared with lean cats, obese cats had higher insulin (P < 0.001) but similar blood glucose concentrations. EGP was lower in obese cats (P < 0.001) due to lower glycogenolysis and gluconeogenesis (GNG; P < 0.03). Insulin, body mass index, and girth correlated negatively with EGP (P < 0.003). Female obese cats had approximately 1.5 times higher fluxes through phosphoenolpyruvate carboxykinase (P < 0.02) and citrate synthase (P < 0.05) than male obese cats. However, GNG was not higher because pyruvate cycling was increased 1.5-fold (P < 0.03). These results support the notion that fasted obese cats have lower hepatic EGP compared with lean cats and are still capable of maintaining fasting euglycemia, despite the well-documented existence of peripheral insulin resistance in obese cats. Our data further suggest that sex-related differences exist in the regulation of hepatic glucose metabolism in obese cats, suggesting that pyruvate cycling acts as a controlling mechanism to modulate EGP. Increased pyruvate cycling could therefore be an important factor in modulating the diabetes risk in female cats.

Layer-specific anatomical, physiological and functional MRI of the retina

Most retinal imaging has been performed using optical techniques. This paper reviews alternative retinal imaging methods based on MRI performed with spatial resolution sufficient to resolve multiple well-defined retinal layers. The development of these MRI technologies to study retinal anatomy, physiology (blood flow, blood volume, and oxygenation) and function, and their applications to the study of normal retinas, retinal degeneration and diabetic retinopathy in animal models are discussed. Although the spatiotemporal resolution of MRI is poorer than that of optical imaging techniques, it is unhampered by media opacity and can thus image all retinal and pararetinal structures, and has the potential to provide multiple unique clinically relevant data in a single setting and could thus complement existing retinal imaging techniques. In turn, the highly structured retina with well-defined layers is an excellent model for advancing emerging high-resolution anatomical, physiological and functional MRI technologies.

Layer-specific anatomical, physiological and functional MRI of the retina

Most retinal imaging has been performed using optical techniques. This paper reviews alternative retinal imaging methods based on MRI performed with spatial resolution sufficient to resolve multiple well-defined retinal layers. The development of these MRI technologies to study retinal anatomy, physiology (blood flow, blood volume, and oxygenation) and function, and their applications to the study of normal retinas, retinal degeneration and diabetic retinopathy in animal models are discussed. Although the spatiotemporal resolution of MRI is poorer than that of optical imaging techniques, it is unhampered by media opacity and can thus image all retinal and pararetinal structures, and has the potential to provide multiple unique clinically relevant data in a single setting and could thus complement existing retinal imaging techniques. In turn, the highly structured retina with well-defined layers is an excellent model for advancing emerging high-resolution anatomical, physiological and functional MRI technologies.

Blood flow magnetic resonance imaging of retinal degeneration

PURPOSE

This study aims to investigate quantitative basal blood flow as well as hypercapnia- and hyperoxia-induced blood flow changes in the retinas of the Royal College of Surgeons (RCS) rats with spontaneous retinal degeneration, and to compare with those of normal rat retinas.

METHODS

Experiments were performed on male RCS rats at post-natal days P90 (n=4) and P220 (n=5), and on age-matched controls at P90 (n=7) and P220 (n=6). Hyperoxic (100% O(2)) and hypercapnic (5% CO(2), 21% O(2), balance N(2)) challenges were used to modulate blood flow. Quantitative baseline blood flow, and hypercapnia- and hyperoxia-induced blood flow changes in the retinas were imaged using continuous arterial spin labeling MRI at 90 x 90 x 1500 microm.

RESULTS

In the normal rat retinas, basal blood flow of the whole-retina was 5.5 mL/gram per min, significantly higher than those reported in the brain (approximately 1 mL/gram per min). Hyperoxia decreased blood flow due to vasoconstriction and hypercapnia increased blood flow due to vasodilation in the normal retinas. In the RCS rat retinas, basal blood flow was diminished significantly (P<0.05). Interestingly, absolute hyperoxia- and hypercapnia-induced blood flow changes in the RCS retinas were not statistically different from those in the normal retinas (P>0.05). However, blood flow percent changes in RCS retinas were significantly larger than in normal retinas due to lower basal blood flow in the RCS retinas.

CONCLUSIONS

Retinal degeneration markedly reduces basal blood flow but does not appear to impair vascular reactivity. These data also suggest caution when interpreting relative stimulus-evoked functional MRI changes in diseased states where basal parameters are significantly perturbed. Quantitative blood flow MRI may serve as a valuable tool to study the retina without depth limitation.

Hepatic insulin gene therapy normalizes diurnal fluctuation of oxidative metabolism in diabetic BB/Wor rats

Previous studies of hepatic insulin gene therapy (HIGT) focused on glycemic effects of insulin produced from hepatocytes. In this study, we extend the observations of glycemic control with metabolically regulated HIGT to include systemic responses and whole-body metabolism. An insulin transgene was administered with an adenoviral vector [Ad/(GlRE)(3)BP1-2xfur] to livers of BB/Wor rats made diabetic with polyinosinic polycytidilic acid (poly-I:C) (HIGT group), and results compared with nondiabetic controls (non-DM), and diabetic rats receiving different doses of continuous-release insulin implants (DM-low BG and DM-high BG). Blood glucose and growth normalized in HIGT, with lower systemic insulin levels, elevated glucagon, and increased heat production compared with non-DM. Minimal regulation of systemic insulin levels were observed with HIGT, yet the animals maintained normal switching from carbohydrate to lipid metabolism determined by respiratory quotients (RQs), and tolerated 24-hour fasts without severe hypoglycemia. HIGT did not restore serum lipids as we observed increased triglycerides (TGs) and increased free fatty acids, but reduced weight of visceral fat pads despite normal total body fat content and retroperitoneal fat depots. HIGT favorably affects blood glucose, normalizes metabolic switching in diabetic rats, and reduces intra-abdominal fat deposition.

Adeno-associated viral delivery of a metabolically regulated insulin transgene to hepatocytes

Transduction with a liver specific, metabolically responsive insulin transgene produces near-normal blood sugars in STZ-diabetic rats. To overcome the limited duration of hepatic transgene expression induced by E1A-deleted adenoviral vectors, we evaluated recombinant adeno-associated virus (rAAV2) for cell type specificity and glucose responsiveness in vitro. Co-infection of AAV2 containing the glucose responsive, liver-specific (GlRE)(3)BP-1 promoter with an empty adenovirus enhanced transduction efficiency, and shortened the duration of transgene expression in HepG2 hepatoma cells, but not primary hepatocytes. However, in the context of rAAV2, (GlRE)(3)BP-1 promoter activity remained confined to cells of hepatocyte lineage, and retained glucose responsiveness. While isolated infection with an insulin expressing rAAV2 failed to attenuate blood sugars in diabetic mice, adenoviral co-administration with the same rAAV2 induced transient, near-normal random blood sugars in a diabetic animal. We conclude that rAAV2 can induce metabolically responsive insulin secretion from hepatocytes in vitro and in vivo. However, alternative AAV serotypes will likely be required to efficiently deliver therapeutic genes to the liver for the treatment of diabetes mellitus.

Teaching diabetes to Middle-School students with the www.2aida.net AIDA online diabetes software simulator

INTRODUCTION

The lifetime risk of developing diabetes for students born in the new millennium in the United States is estimated to be 27% to 52%. Many students need to learn about diabetes for their personal care, or desire to learn about diabetes to develop a career in healthcare. Most teenagers are adept at learning through Web-based computer tools.

METHODS

Twenty-one students entering 8(th) and 9(th) grades (aged 12 to 14 years old) enrolled in a Biotechnology Summer Camp focused on diabetes. Lectures on pathophysiology and clinical aspects of diabetes were followed by simulated cases using the AIDA online diabetes software simulator accessed via the internet at www.2aida.net. Two cases demonstrated glycemic effects and pharmacokinetics of insulin administration, diet, and exercise in insulin-dependent (Type 1) diabetes and non-insulin-dependent (Type 2) diabetes. Students filled out standardized evaluations at the end of the session to assess receptiveness to this type of learning; opinions on the utility, information, and ease of use; and perceived risks of using the online simulator to understand diabetes.

RESULTS

All students were receptive to this educational tool. The majority found AIDA online useful (17/21 [81%]), educational (21/21 [100%]), worthy of wider distribution (20/21 [95%]), and would recommend the program to others with diabetes or wanting to learn about diabetes (18/21 [86%]). A minority (2/21 [9.5%]) found the program risky regarding the information given to the students. Positive comments included the ability to visualize concepts being taught in earlier lectures, and recognized the rigors required to manage diabetes. Fewer negative comments reflected frustration with the web-based user interface, the course materials, or difficulty in achieving good simulated glycemic control.

DISCUSSION

Teaching pathophysiology of diabetes and pharmacology of insulin to middle school students is enhanced with the AIDA online diabetes simulator. Future versions of this program, and development of similar programs, could be useful in teaching adolescents who have diabetes, and might help stimulate interested students to learn more about the care of people with diabetes.

Structural and functional MRI reveals multiple retinal layers

MRI is a noninvasive diagnostic modality that reveals anatomy, physiology, and function in vivo without depth limitation or optical interference. MRI application to the retina, however, remains challenging. We improved spatial resolution to resolve layer-specific structure and functional responses in the retina and confirmed the laminar resolution in an established animal model of retinal degeneration. Structural MRI of normal rat retinas revealed three bands corresponding histologically to (i) the combined ganglion cell layer/inner nuclear layer plus the embedded retinal vessels, (ii) the avascular outer nuclear (photoreceptor) layer and its photoreceptor segments, and (iii) the choroidal vascular layer. Imaging with an intravascular contrast agent (gadolinium-diethylene-tri-amine-pentaacetic acid) enhanced the retinal and choroidal vascular layers bounding the retina, but not the avascular outer nuclear layer and the vitreous. Similarly, blood-oxygen-level-dependent (BOLD) functional MRI revealed layer-specific responses to hyperoxia and hypercapnia. Importantly, layer-specific BOLD responses in the two vascular layers were divergent, suggesting the two vasculatures are differentially regulated. To corroborate sensitivity and specificity, we applied layer-specific MRI to document photoreceptor degeneration in Royal College of Surgeons rats. Consistent with histology, layer-specific MRI detected degeneration of the outer nuclear layer. Surprisingly, MRI revealed increased thickness in the choroidal vascular layer and diminished BOLD responses to hyperoxia and hypercapnia in the Royal College of Surgeons rat retinas, suggesting perturbation of vascular reactivity secondary to photoreceptor loss. We conclude that MRI is a powerful investigative tool capable of resolving lamina-specific structures and functional responses in the retina as well as probing lamina-specific changes in retinal diseases.

Hepatic insulin gene therapy prevents deterioration of vascular function and improves adipocytokine profile in STZ-diabetic rats

Hepatic insulin gene therapy (HIGT) ameliorates hyperglycemia in diabetic rodents, suggesting that similar approaches may eventually provide a means to improve treatment of diabetes mellitus. However, whether the metabolic and hormonal changes produced by HIGT benefit vascular function remains unclear. The impact of HIGT on endothelium-dependent vasodilation, nitrosyl-hemoglobin content (NO-Hb), and insulin sensitivity were studied using aortic ring preparations, electron spin resonance spectroscopy (ESR), homeostasis assessment of insulin resistance (HOMA-IR) calculations, and insulin tolerance testing (ITT). Data were correlated with selected hormone and adipocytokine concentrations. Rats made diabetic with streptozotocin were treated with subcutaneous insulin pellets dosed to sustain body weights and hyperglycemia or with HIGT; nondiabetic rats served as controls. Hyperglycemic rats demonstrated impaired endothelium-dependent vasodilation, reduced levels of NO-Hb, and diminished insulin, leptin, and adiponectin concentrations compared with controls. In contrast, HIGT treatment significantly reduced blood sugars and sustained both endothelium-mediated vasodilation and NO-Hb at control levels. HOMA-IR calculations and ITT indicated enhanced insulin sensitivity among HIGT-treated rats. HIGT partially restored suppressed leptin levels in hyperglycemic rats and increased adiponectin concentrations to supranormal levels, consistent with indicators of insulin sensitivity. Our findings indicate that the metabolic milieu produced by HIGT is sufficient to preserve vascular function in diabetic rodents. These data suggest that improved glycemia, induction of a beneficial adipocytokine profile, and enhanced insulin sensitivity combine to preserve endothelium-dependent vascular function in HIGT-treated diabetic rats. Consequently, HIGT may represent a novel and efficacious approach to reduce diabetes-associated vascular dysfunction.

Host Cells Reduce Glucose Uptake and Glycogen Deposition in Response to Hepatic Insulin Gene Therapy

BACKGROUND

Hepatic insulin gene therapy (HIGT) restores weight gain and near-normal glycemia in rodent models of insulin-deficient diabetes mellitus. However, the effect of transgenic insulin on endogenous genes and recipient cell function is relatively unexplored. To investigate hepatocellular effects of transgenic insulin expression, we evaluated intermediary glucose metabolism in primary cultured hepatocytes treated with HIGT.

METHODS

Rat hepatocytes were transduced with adenovirus expressing a glucose-responsive human insulin transgene and cultured in high-glucose and high-insulin conditions. We determined glycogen content in cell cultures and intact liver directly. Glycogenolysis was compared using glucose production of cultured cells. Glucose uptake, oxidative, and glycolytic processing were determined by radiotracer analysis or direct end-product assessment. Quantitative real-time reverse transcriptase polymerase chain reaction was used to determine expression of glucose transporter 2 (GLUT2) and glucokinase genes. GLUT2 protein abundance was determined by Western blot analysis.

RESULTS

HIGT-treated hepatocytes contained significantly less glycogen than either untreated hepatocytes or those treated with an empty virus. Glucose release owing to glycogenolysis remained normal. However, HIGT treatment significantly impaired glucose uptake and processing. Metabolic synthetic processes were not generally inhibited, as indicated by enhanced beta-hydroxybutyrate secretion. While preserving cell viability, HIGT treatment diminished expression of both glucokinase and GLUT2. In HIGT-treated streptozocin-treated diabetic rats, total liver glycogen was intermediate between diabetic animals and normal controls.

CONCLUSIONS

These results suggest gene-specific effects in recipient hepatocytes following HIGT treatment and underscore the need for expanded studies examining host cell responses to the transfer of metabolically active transgenes.

Glucose-responsive hepatic insulin gene therapy of spontaneously diabetic BB/Wor rats

Hepatic insulin gene therapy (HIGT) ameliorates hyperglycemia in multiple rodent models of diabetes mellitus, with variable degrees of glucose control. We demonstrate here that adenoviral delivery of a glucose-regulated transgene into rat hepatocytes produces near-normal glycemia in spontaneously diabetic BB/Wor rats without administration of exogenous insulin. We compared growth, glycemia, counterregulatory hormones, and lipids in HIGT-treated diabetic rats to nondiabetic rats and diabetic rats treated with either insulin injections or sustained-release insulin pellets. HIGT-treated rats achieved near-normal blood glucose levels within 1 week and maintained glycemic control for up to 3 months. Rats treated with sustained release insulin implants had similar blood sugars, but more hypoglycemia and gained more weight than HIGT-treated rats. HIGT-treated rats normalized blood glucose within 2 hr after a glucose load, and tolerated a 24-hr fast without hypoglycemia. HIGT treatment suppressed ketogenesis similarly to peripheral insulin. However, glucagon levels and free fatty acids were increased in HIGT-treated rats compared to either nondiabetic controls or rats treated with exogenous insulin. In addition to extending successful application of HIGT to a rat model of autoimmune diabetes, these findings emphasize the relative contribution of hepatic insulin effect in the metabolic stabilization of diabetes mellitus.

Implementing evidence-based diabetes care in geriatric populations. The chronic care model

The prevalence of diabetes mellitus in older adults continues to increase and their health care is often suboptimal. The chronic care model discussed in this article provides a framework for change in the practice and organization of care for chronic illnesses, including diabetes. This model facilitates optimal care of both individuals and populations, including older adults with diabetes. Evidence-based, clinical interventions that can be implemented in the physician's practice are discussed.

Diabetes in older adults. Overview of AGS guidelines for the treatment of diabetes mellitus in geriatric populations

The recently published guidelines from the California Healthcare Foundation/American Geriatrics Society Panel on Improving Care for Elders with Diabetes provide recommendations that should help improve care in that population. This paper will summarize the guidelines and indicate which recommendations are evidence-based and which are based on expert opinion, as some aspects of the guidelines have not been examined in controlled clinical trials. Practitioners need to apply approaches to care that consider level of function and the patient's and family's wishes and values.

Acoustic and perceptual evaluation of laryngeal reinnervation by ansa cervicalis transfer

OBJECTIVES/HYPOTHESIS

To evaluate the acoustic and perceptual results of laryngeal reinnervation with ansa cervicalis to recurrent laryngeal nerve anastomosis.

STUDY DESIGN

Retrospective study of voice samples from 12 patients with unilateral recurrent laryngeal nerve paralysis, treated with ansa cervicalis to recurrent laryngeal nerve anastomosis. Samples were recorded before surgery and at least 8 months after surgery.

METHODS

The samples were subjected to several acoustic analyses sensitive to paralytic dysphonia, including cepstral peak prominence, noise-to-harmonics ratio, and measures of frequency and amplitude perturbation. The voice samples from the patients were randomized with age- and sex-matched samples from normal subjects and judged by trained listeners for overall dysphonia, roughness, breathiness, asthenia, and strain. The preoperative and postoperative results were compared statistically, and the postoperative results were compared with the matched normal subjects.

RESULTS

As a group, the patients showed improvement (P < .05) in cepstral peak prominence, frequency perturbation, and perceptual judgments of overall dysphonia, breathiness, and asthenia. The best results occurred in patients with isolated vocal fold paralysis. The postoperative group as a whole did not improve to the level seen in matched normals. Suboptimal results were seen primarily in patients with untreated laryngeal or extralaryngeal pathology beyond the laryngeal paralysis.

CONCLUSIONS

These data suggest that laryngeal reinnervation has the potential to bring about a return to normal or near-normal voice in patients with isolated unilateral vocal fold paralysis.

Quantitative RT-PCR measurement of cytochromes p450 1A1, 1B1, and 2B7, microsomal epoxide hydrolase, and NADPH oxidoreductase expression in lung cells of smokers and nonsmokers

Bronchial epithelial cells (BEC) are the progenitors of bronchogenic carcinomas and are exposed to polycyclic aromatic hydrocarbon (PAH) procarcinogens through inhalation of combustion products. PAH are converted to carcinogenic molecules through a combination of monoxygenation by cytochrome p450 (CYP) enzymes in the presence of NADPH oxidoreductase (OR) and hydrolysis by microsomal epoxide hydrolase (mEH). In artificial systems, the relative expression of these genes determines whether carcinogenic or noncarcinogenic species are generated during metabolism. This relationship was explored in humans by using quantitative competitive reverse transcriptase polymerase chain reaction amplification to determine the range of expression of CYP1A1, CYP1B1, mEH, and NADPH OR in BEC recovered from 10 nonsmokers and 9 smokers. CYP2B7 expression was evaluated because, although little is known of its substrate specificity, it is expressed at high levels in human lung tissue. CYP1A1 and CYP1B1 were expressed in BEC at significantly different levels (P < 0.05) in the 9 smokers at 1.4 +/- 2.3 x 10(4) and 2.4 +/- 3.2 x 10(3) molecules/10(6) beta-actin molecules (mean +/- STD), respectively, but each was measurable in only one of the 10 nonsmokers. There was significant inter-individual variation (P < 0.05) in both CYP1A1 and CYP1B1 expression among the subjects for whom sufficient data were obtained. The inducibility of human BEC CYP1A1 gene by PAH exposure was confirmed in vitro by incubating cultured immortalized human BEC with beta-naphthoflavone and observing a > 6-fold induction of CYP1A1 after 24 h. In contrast to BEC, alveolar macrophages expressed CYP1A1 at low (30-70 molecules/10(6) beta-actin molecules) to unmeasurable levels in both smokers and nonsmokers. There was no significant difference in expression of mEH, CYP2B7, or NADPH OR in smokers compared with nonsmokers. The inter-individual variation in absolute and relative expression of PAH metabolism enzymes in BEC reported here supports the hypothesis that inter-individual variation in ability to activate/inactivate inhaled PAH carcinogens accounts for at least some of the inter-individual variation in risk for bronchogenic carcinoma.