Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Decreased rates of hypoglycemia following implementation of a comprehensive computerized insulin order set and titration algorithm in the inpatient setting

OBJECTIVES

More than one-third of hospitalized patients have hyperglycemia. Despite evidence that improving glycemic control leads to better outcomes, achieving recognized targets remains a challenge. The objective of this study was to evaluate the implementation of a computerized insulin order set and titration algorithm on rates of hypoglycemia and overall inpatient glycemic control.

METHODS

A prospective observational study evaluating the impact of a glycemic order set and titration algorithm in an academic medical center in non-critical care medical and surgical inpatients. The initial intervention was hospital-wide implementation of a comprehensive insulin order set. The secondary intervention was initiation of an insulin titration algorithm in two pilot medicine inpatient units. Point of care testing blood glucose reports were analyzed. These reports included rates of hypoglycemia (BG < 70 mg/dL) and hyperglycemia (BG >200 mg/dL in phase 1, BG > 180 mg/dL in phase 2).

RESULTS

In the first phase of the study, implementation of the insulin order set was associated with decreased rates of hypoglycemia (1.92% vs 1.61%; p < 0.001) and increased rates of hyperglycemia (24.02% vs 27.27%; p < 0.001) from 2010 to 2011. In the second phase, addition of a titration algorithm was associated with decreased rates of hypoglycemia (2.57% vs 1.82%; p = 0.039) and increased rates of hyperglycemia (31.76% vs 41.33%; p < 0.001) from 2012 to 2013.

CONCLUSIONS

A comprehensive computerized insulin order set and titration algorithm significantly decreased rates of hypoglycemia. This significant reduction in hypoglycemia was associated with increased rates of hyperglycemia. Hardwiring the algorithm into the electronic medical record may foster adoption.

Association between 7 years of intensive treatment of type 1 diabetes and long-term mortality

IMPORTANCE

Whether mortality in type 1 diabetes mellitus is affected following intensive glycemic therapy has not been established.

OBJECTIVE

To determine whether mortality differed between the original intensive and conventional treatment groups in the long-term follow-up of the Diabetes Control and Complications Trial (DCCT) cohort.

DESIGN, SETTING, AND PARTICIPANTS

After the DCCT (1983-1993) ended, participants were followed up in a multisite (27 US and Canadian academic clinical centers) observational study (Epidemiology of Diabetes Control and Complications [EDIC]) until December 31, 2012. Participants were 1441 healthy volunteers with diabetes mellitus who, at baseline, were 13 to 39 years of age with 1 to 15 years of diabetes duration and no or early microvascular complications, and without hypertension, preexisting cardiovascular disease, or other potentially life-threatening disease.

INTERVENTIONS AND EXPOSURES

During the clinical trial, participants were randomly assigned to receive intensive therapy (n = 711) aimed at achieving glycemia as close to the nondiabetic range as safely possible, or conventional therapy (n = 730) with the goal of avoiding symptomatic hypoglycemia and hyperglycemia. At the end of the DCCT, after a mean of 6.5 years, intensive therapy was taught and recommended to all participants and diabetes care was returned to personal physicians.

MAIN OUTCOMES AND MEASURES

Total and cause-specific mortality was assessed through annual contact with family and friends and through records over 27 years' mean follow-up.

RESULTS

Vital status was ascertained for 1429 (99.2%) participants. There were 107 deaths, 64 in the conventional and 43 in the intensive group. The absolute risk difference was -109 per 100,000 patient-years (95% CI, -218 to -1), with lower all-cause mortality risk in the intensive therapy group (hazard ratio [HR] = 0.67 [95% CI, 0.46-0.99]; P = .045). Primary causes of death were cardiovascular disease (24 deaths; 22.4%), cancer (21 deaths; 19.6%), acute diabetes complications (19 deaths; 17.8%), and accidents or suicide (18 deaths; 16.8%). Higher levels of glycated hemoglobin (HbA1c) were associated with all-cause mortality (HR = 1.56 [95% CI, 1.35-1.81 per 10% relative increase in HbA1c]; P < .001), as well as the development of albuminuria (HR = 2.20 [95% CI, 1.46-3.31]; P < .001).

CONCLUSIONS AND RELEVANCE

After a mean of 27 years' follow-up of patients with type 1 diabetes, 6.5 years of initial intensive diabetes therapy was associated with a modestly lower all-cause mortality rate when compared with conventional therapy.

TRIAL REGISTRATION

clinicaltrials.gov Identifiers: NCT00360815 and NCT00360893.

Medical versus surgical treatment of type 2 diabetes: the search for level 1 evidence

Data from observational and nonrandomized comparative studies have shown a dramatic effect of bariatric surgery on type 2 diabetes mellitus (T2DM), including in nonobese patients. However, a relative paucity of level 1 evidence is available to define the exact role of surgery as a treatment modality for T2DM, especially in less obese subjects. Performing randomized clinical trials in this field, however, poses significant and specific challenges for the study design. We have addressed such challenges in a carefully designed randomized controlled trial comparing glycemic control with optimal medical management versus Roux-en-Y gastric bypass in overweight to mildly obese patients with T2DM mellitus (body mass index 26-35 kg/m(2)). The present report describes the rationale and design of the Weill Cornell Medical College study. In addition to glycemic endpoints, however, clinical trials should also investigate the effect of surgery on cardiovascular risk or T2DM-specific morbidity. Addressing these endpoints would entail large, randomized clinical trials with prolonged period of observation and ideally a multicenter study design. Such a multisite trial poses substantial logistical and financial challenges, which would predictably delay rather than accelerate progress of research in this field. A consortium of centers performing independent small and medium size randomized clinical trials may provide a more realistic and feasible approach. In this paper, we present an overview of on-going randomized clinical trials in this field and propose a worldwide consortium of randomized controlled trials (WORLDCoRDS) using the Weill Cornell Medical College protocol. The aim of this consortium is to standardize research in T2DM surgery and timely accumulate homogeneous data that can help assess the effects of GI surgery on cardiovascular risk and T2DM-related mortality and morbidity.

Human vascular endothelial cells: a model system for studying vascular inflammation in diabetes and atherosclerosis

The vascular endothelium is the inner lining of blood vessels serving as autocrine and paracrine organ that regulates vascular wall function. Endothelial dysfunction is recognized as initial step in the atherosclerotic process and is well advanced in diabetes, even before the manifestation of end-organ damage. Strategies capable of assessing changes in vascular endothelium at the preclinical stage hold potential to refine cardiovascular risk. In vitro cell culture is useful in understanding the interaction of endothelial cells with various mediators; however, it is often criticized due to the uncertain relevance of results to humans. Although circulating endothelial cells, endothelial microparticles, and progenitor cells opened the way for ex vivo studies, a recently described method for obtaining primary endothelial cells through endovascular biopsy allows direct characterization of endothelial phenotype in humans. In this article, we appraise the use of endothelial cell-based methodologies to study vascular inflammation in diabetes and atherosclerosis.

Development and validation of a patient self-assessment score for diabetes risk

BACKGROUND

National guidelines disagree on who should be screened for undiagnosed diabetes. No existing diabetes risk score is highly generalizable or widely followed.

OBJECTIVE

To develop a new diabetes screening score and compare it with other available screening instruments (Centers for Disease Control and Prevention, American Diabetes Association, and U.S. Preventive Services Task Force guidelines; 2 American Diabetes Association risk questionnaires; and the Rotterdam model).

DESIGN

Cross-sectional data.

SETTING

NHANES (National Health and Nutrition Examination Survey) 1999 to 2004 for model development and 2005 to 2006, plus a combined cohort of 2 community studies, ARIC (Atherosclerosis Risk in Communities) Study and CHS (Cardiovascular Health Study), for validation.

PARTICIPANTS

U.S. adults aged 20 years or older.

MEASUREMENTS

A risk-scoring algorithm for undiagnosed diabetes, defined as fasting plasma glucose level of 7.0 mmol/L (126 mg/dL) or greater without known diabetes, was developed in the development data set. Logistic regression was used to determine which participant characteristics were independently associated with undiagnosed diabetes. The new algorithm and other methods were evaluated by standard diagnostic and feasibility measures.

RESULTS

Age, sex, family history of diabetes, history of hypertension, obesity, and physical activity were associated with undiagnosed diabetes. In NHANES (ARIC/CHS), the cut-point of 5 or more points selected 35% (40%) of persons for diabetes screening and yielded a sensitivity of 79% (72%), specificity of 67% (62%), positive predictive value of 10% (10%), and positive likelihood ratio of 2.39 (1.89). In contrast, the comparison scores yielded a sensitivity of 44% to 100%, specificity of 10% to 73%, positive predictive value of 5% to 8%, and positive likelihood ratio of 1.11 to 1.98.

LIMITATION

Data during pregnancy were not available.

CONCLUSION

This easy-to-implement diabetes screening score seems to demonstrate improvements over existing methods. Studies are needed to evaluate it in diverse populations in real-world settings.

PRIMARY FUNDING SOURCE

Clinical and Translational Science Center at Weill Cornell Medical College.

Development and validation of a patient self-assessment score for diabetes risk

BACKGROUND

National guidelines disagree on who should be screened for undiagnosed diabetes. No existing diabetes risk score is highly generalizable or widely followed.

OBJECTIVE

To develop a new diabetes screening score and compare it with other available screening instruments (Centers for Disease Control and Prevention, American Diabetes Association, and U.S. Preventive Services Task Force guidelines; 2 American Diabetes Association risk questionnaires; and the Rotterdam model).

DESIGN

Cross-sectional data.

SETTING

NHANES (National Health and Nutrition Examination Survey) 1999 to 2004 for model development and 2005 to 2006, plus a combined cohort of 2 community studies, ARIC (Atherosclerosis Risk in Communities) Study and CHS (Cardiovascular Health Study), for validation.

PARTICIPANTS

U.S. adults aged 20 years or older.

MEASUREMENTS

A risk-scoring algorithm for undiagnosed diabetes, defined as fasting plasma glucose level of 7.0 mmol/L (126 mg/dL) or greater without known diabetes, was developed in the development data set. Logistic regression was used to determine which participant characteristics were independently associated with undiagnosed diabetes. The new algorithm and other methods were evaluated by standard diagnostic and feasibility measures.

RESULTS

Age, sex, family history of diabetes, history of hypertension, obesity, and physical activity were associated with undiagnosed diabetes. In NHANES (ARIC/CHS), the cut-point of 5 or more points selected 35% (40%) of persons for diabetes screening and yielded a sensitivity of 79% (72%), specificity of 67% (62%), positive predictive value of 10% (10%), and positive likelihood ratio of 2.39 (1.89). In contrast, the comparison scores yielded a sensitivity of 44% to 100%, specificity of 10% to 73%, positive predictive value of 5% to 8%, and positive likelihood ratio of 1.11 to 1.98.

LIMITATION

Data during pregnancy were not available.

CONCLUSION

This easy-to-implement diabetes screening score seems to demonstrate improvements over existing methods. Studies are needed to evaluate it in diverse populations in real-world settings.

PRIMARY FUNDING SOURCE

Clinical and Translational Science Center at Weill Cornell Medical College.

Severe hypoglycemia monitoring and risk management procedures in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial

Hypoglycemia is a potentially serious side effect of blood glucose lowering in diabetes mellitus. The intensive glycemia treatment arm of the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial is designed to treat patients with type 2 diabetes with target glycemia within the normal range (ie, glycosylated hemoglobin <6%). Because it is known that treating glycemia to such a low level in patients with diabetes will result in episodes of hypoglycemia, it is necessary to address prevention and treatment of such episodes to ensure patient safety. Thus, several approaches are being taken in the ACCORD trial to prevent initial episodes of severe hypoglycemia, to monitor the frequency of episodes that do occur, and to prevent recurrence. This report describes the processes used in the ACCORD trial, including the definition of severe hypoglycemia, the type of education provided to participants and staff members to prevent initial and subsequent episodes of severe hypoglycemia, and the monitoring systems implemented to identify severe hypoglycemia and prevent its recurrence. The ACCORD trial conducts review and oversight of individual cases of severe hypoglycemia and monitors rates of severe hypoglycemia by clinical site and treatment arm. If the ACCORD intensive glycemia treatment is found to be efficacious in preventing cardiovascular disease events, assessment of the risk and benefit will be essential. In addition, translation of the principles behind the monitoring of severe hypoglycemia in ACCORD into feasible strategies for use in clinical practice will be needed.

Lack of postprandial leptin peaks in patients with type 2 diabetes mellitus

Leptin production by the adipocyte is acutely stimulated by insulin in vitro. In normal individuals, postprandial insulin peaks are not accompanied by corresponding changes in circulating leptin. Postprandial regulation of leptin in individuals with type 2 diabetes, to our knowledge, has not been previously examined in detail. We examined the effect of meals on circulating leptin levels in six patients with type 2 diabetes who were not treated with insulin and in seven normal individuals. After informed consent was obtained, all subjects were admitted to the General Clinical Research Center for 6 days. They consumed four meals daily (breakfast, lunch, dinner and snack). Eighteen blood samples were drawn between 7.40 a.m. and midnight for the determination of serum leptin, insulin and glucose levels. Postprandial peaks were clearly identifiable for glucose and insulin levels both in normal subjects and in those with type 2 diabetes. However, no postprandial peaks of leptin levels were present. Correlation analysis demonstrated a lack of correlation between leptin levels and the levels of glucose or insulin. We conclude that, in spite of the presence of postprandial insulin peaks, there are no acute changes in circulating leptin levels postprandially in patients with type 2 diabetes who are not on insulin therapy. In this regard, in-vivo regulation of leptin by meals in patients with type 2 diabetes is similar to that in normal individuals.

New directions in type 2 diabetes mellitus: an update of current oral antidiabetic therapy

This article reviewed the relevant literature including published clinical trials and reviews on currently available oral hypoglycemic agents. Results showed that the benefits of glycemic control have been established through multiple clinical trials. Long-term control of blood glucose levels in type 1 and type 2 diabetic patients will decrease the incidence and prolong the time until progression of diabetic retinopathy, nephropathy, and neuropathy. Our increased understanding of the pathophysiology behind type 2 diabetes has led to the development of many new agents that are aimed at treating the underlying insulin resistance and relative insulinopenia. The sulfonylureas as a group have been used for many years and act by stimulating insulin secretion. They are useful alone or as combination therapy with insulin or another oral hypoglycemic agent. The biguanides act by decreasing hepatic glucose production and by increasing peripheral insulin sensitivity. The alpha-glucosidase inhibitors act nonsystemically by blocking the metabolism of digested polysaccharides and therefore lowering the amount of carbohydrate absorbed in a meal. Benzoic acid derivatives act in a manner similar to that of sulfonylureas by enhancing pancreatic insulin production. They offer a shorter duration of action, lowering the risk of hypoglycemia. The thiazolidinediones increase peripheral insulin sensitivity and are effective as both monotherapy and combination therapy. Oral hypoglycemic agents, when properly administered, are very effective in controlling type 2 diabetes and preventing long-term complications.

Cellular mechanisms of insulin resistance in non-insulin-dependent (type II) diabetes

Recent studies have led to an enhanced understanding of cellular alterations that may play an important role in the pathophysiology of non-insulin-dependent diabetes mellitus (NIDDM). The insulin receptor links insulin binding at the cell surface to intracellular activation of insulin's effects. This transducer function involves the tyrosine kinase property of the beta-subunit of the receptor. It was found that adipocytes from subjects with NIDDM had a 50 to 80 percent reduction in insulin-stimulated receptor kinase activity compared with their non-diabetic counterparts. This defect was relatively specific for the diabetic state since no decrease was observed in insulin-resistant non-diabetic obese subjects. The reduction in kinase activity was accounted for by changes in the ratio of two pools of receptors, both of which bind insulin but only one of which is capable of tyrosine autophosphorylation and subsequent kinase activation; 43 percent of the receptors from non-diabetic subjects were capable of autophosphorylation compared with only 14 percent in the NIDDM group. A major component of cellular insulin resistance in NIDDM involves the glucose transport system. Exposure of cells to insulin normally results in enhanced glucose transport mediated by translocation of glucose transporters from a low-density microsomal intracellular pool to the plasma membrane. It was found that cells from NIDDM subjects had a marked depletion of glucose transporters in both plasma membranes and low-density microsomes, relative to obese non-diabetic control participants. Obese non-diabetic persons had a normal number of plasma membrane transporters but a reduced number of low-density microsome transporters in the basal state compared with lean control volunteers; insulin induced the translocation of relatively fewer transporters from the low-density microsome to the plasma membrane in the obese subgroups. In addition to the diminished number of glucose transporters, cells from both NIDDM and obese subjects had impaired functional activity of glucose carriers since decreased whole-cell glucose transport rates could not be entirely explained by the magnitude of the decrement in the number of plasma membrane transporters. Thus, impaired glucose transport is due to both a numerical and functional defect in glucose transporters. The cellular content of high-density microsomal transporters was the same in lean and obese control volunteers and NIDDM subjects, suggesting that transporter synthesis is normal and that cellular depletion results from increased protein turnover once transporters leave the high-density microsomal subfraction.(ABSTRACT TRUNCATED AT 400 WORDS)

Cholinergic but not serotonergic mediation of exercise-induced growth hormone secretion

In order to clarify the roles of cholinergic and serotonergic neurotransmission in the mediation of exercise-induced growth hormone (GH) release, normal young volunteers of both sexes were studied. Exercise was for 20 minutes at 800 kpm for the men and 500 kpm for the women. Pretreatment with 0.4 mg atropine 1 hour prior to exercise, or with methysergide 2 mg po q 6 h for 48 hours prior to exercise, were used to evaluate the influence of cholinergic and serotonergic blockade, respectively. Five of the ten men studied failed to raise GH values with exercise, perhaps because the exercise was not vigorous enough for their high degree of fitness. Of three non-responders restudied, at the same workload, one responded on the second occasion. The mean peak GH with exercise 13.4 +/- 3.27 ng/ml, was reduced to 2.4 +/- 1.28 ng/ml (p less than 0.01) after atropine, but was unaffected by methysergide (15.2 +/- 6.58 ng/ml, p greater than 0.5). Prolactin did not rise with exercise, and was not affected by atropine, but lowered by methysergide as expected. Cholinergic neurotransmission therefore represents a key link in exercise-induced GH secretion, but serotonergic influences are probably not involved.