The Relationship between AKI and CKD in Patients with Type 2 Diabetes: An Observational Cohort Study

BACKGROUND

There are few observational studies evaluating the risk of AKI in people with type 2 diabetes, and even fewer simultaneously investigating AKI and CKD in this population. This limits understanding of the interplay between AKI and CKD in people with type 2 diabetes compared with the nondiabetic population.

METHODS

In this retrospective, cohort study of participants with or without type 2 diabetes, we used electronic healthcare records to evaluate rates of AKI and various statistical methods to determine their relationship to CKD status and further renal function decline.

RESULTS

We followed the cohort of 16,700 participants (9417 with type 2 diabetes and 7283 controls without diabetes) for a median of 8.2 years. Those with diabetes were more likely than controls to develop AKI (48.6% versus 17.2%, respectively) and have preexisting CKD or CKD that developed during follow-up (46.3% versus 17.2%, respectively). In the absence of CKD, the AKI rate among people with diabetes was nearly five times that of controls (121.5 versus 24.6 per 1000 person-years). Among participants with CKD, AKI rate in people with diabetes was more than twice that of controls (384.8 versus 180.0 per 1000 person-years after CKD diagnostic date, and 109.3 versus 47.4 per 1000 person-years before CKD onset in those developing CKD after recruitment). Decline in eGFR slope before AKI episodes was steeper in people with diabetes versus controls. After AKI episodes, decline in eGFR slope became steeper in people without diabetes, but not among those with diabetes and preexisting CKD.

CONCLUSIONS

Patients with diabetes have significantly higher rates of AKI compared with patients without diabetes, and this remains true for individuals with preexisting CKD.

Genetic Predisposition to Coronary Artery Disease in Type 2 Diabetes Mellitus

BACKGROUND

Coronary artery disease (CAD) is accelerated in subjects with type 2 diabetes mellitus (T2D).

METHODS

To test whether this reflects differential genetic influences on CAD risk in subjects with T2D, we performed a systematic assessment of genetic overlap between CAD and T2D in 66 643 subjects (27 708 with CAD and 24 259 with T2D). Variants showing apparent association with CAD in stratified analyses or evidence of interaction were evaluated in a further 117 787 subjects (16 694 with CAD and 11 537 with T2D).

RESULTS

None of the previously characterized CAD loci was found to have specific effects on CAD in T2D individuals, and a genome-wide interaction analysis found no new variants for CAD that could be considered T2D specific. When we considered the overall genetic correlations between CAD and its risk factors, we found no substantial differences in these relationships by T2D background.

CONCLUSIONS

This study found no evidence that the genetic architecture of CAD differs in those with T2D compared with those without T2D.

P5004Peripheral neuropathy and increased risk of heart failure: a population-based longitudinal cohort study

Background

One of the main pathophysiological processes thought to be implicated in the development of diabetic cardiomyopathy is a microvascular disease (MiVD) that is prevalent in type 2 diabetes (T2D). However, the role of MiVD in the development of heart failure (HF) is not known. T2D screening programmes identify three types of MiVD – retinopathy, nephropathy and neuropathy. Both retinopathy and nephropathy have been independently associated with the development of incident HF in observational cohort studies. There is less data on peripheral neuropathy and HF outcomes. This study aimed to determine the independent association of diabetic neuropathy with incident HF events in a large longitudinal population cohort of T2D patients with a detailed clinical follow-up that includes available echocardiographic data.

Design

This was a population-based longitudinal cohort study from the Genetics of Diabetes Audit and Research in Tayside Scotland study (GoDARTS) from 1996 to 2016. A total of 9,598 patients with T2D were included with data available on hospital admissions, prescribing and other clinical variables including age, gender, smoking history, duration of T2D, body mass index, systolic blood pressure, glycosylated haemoglobin (HbA1c), triglyceride, total LDL and HDL cholesterol levels. Neuropathy cases were identified using a well-validated record linkage method utilising neuropathic drug prescription records to identify cases of neuropathic pain and to monofilament testing that is used to diagnose neuropathy.

Results

There were 805 HF events. After adjustment for clinical variables, the presence of painful neuropathy related to a 57% increased risk of incident HF (HR 1.57, 95% CI = 1.32–1.89, p<0.001). A similar risk was also observed with diabetic neuropathy identified by monofilament testing with a 52% (HR 1.52, CI = 1.013–1.225, P<0.05) increased risk of incident HF.

Conclusions and relevance

Peripheral neuropathy, a feature of MiVD, may be pathophysiologically associated with the development of HF in patients with T2D and may be a therapeutic target.

Novel Blood Pressure Locus and Gene Discovery Using Genome-Wide Association Study and Expression Data Sets From Blood and the Kidney

Elevated blood pressure is a major risk factor for cardiovascular disease and has a substantial genetic contribution. Genetic variation influencing blood pressure has the potential to identify new pharmacological targets for the treatment of hypertension. To discover additional novel blood pressure loci, we used 1000 Genomes Project-based imputation in 150 134 European ancestry individuals and sought significant evidence for independent replication in a further 228 245 individuals. We report 6 new signals of association in or near HSPB7, TNXB, LRP12, LOC283335, SEPT9, and AKT2, and provide new replication evidence for a further 2 signals in EBF2 and NFKBIA. Combining large whole-blood gene expression resources totaling 12 607 individuals, we investigated all novel and previously reported signals and identified 48 genes with evidence for involvement in blood pressure regulation that are significant in multiple resources. Three novel kidney-specific signals were also detected. These robustly implicated genes may provide new leads for therapeutic innovation.

A Low-Frequency Inactivating AKT2 Variant Enriched in the Finnish Population Is Associated With Fasting Insulin Levels and Type 2 Diabetes Risk

To identify novel coding association signals and facilitate characterization of mechanisms influencing glycemic traits and type 2 diabetes risk, we analyzed 109,215 variants derived from exome array genotyping together with an additional 390,225 variants from exome sequence in up to 39,339 normoglycemic individuals from five ancestry groups. We identified a novel association between the coding variant (p.Pro50Thr) in AKT2 and fasting plasma insulin (FI), a gene in which rare fully penetrant mutations are causal for monogenic glycemic disorders. The low-frequency allele is associated with a 12% increase in FI levels. This variant is present at 1.1% frequency in Finns but virtually absent in individuals from other ancestries. Carriers of the FI-increasing allele had increased 2-h insulin values, decreased insulin sensitivity, and increased risk of type 2 diabetes (odds ratio 1.05). In cellular studies, the AKT2-Thr50 protein exhibited a partial loss of function. We extend the allelic spectrum for coding variants in AKT2 associated with disorders of glucose homeostasis and demonstrate bidirectional effects of variants within the pleckstrin homology domain of AKT2.

The genetics of blood pressure regulation and its target organs from association studies in 342,415 individuals

To dissect the genetic architecture of blood pressure and assess effects on target organ damage, we analyzed 128,272 SNPs from targeted and genome-wide arrays in 201,529 individuals of European ancestry, and genotypes from an additional 140,886 individuals were used for validation. We identified 66 blood pressure-associated loci, of which 17 were new; 15 harbored multiple distinct association signals. The 66 index SNPs were enriched for cis-regulatory elements, particularly in vascular endothelial cells, consistent with a primary role in blood pressure control through modulation of vascular tone across multiple tissues. The 66 index SNPs combined in a risk score showed comparable effects in 64,421 individuals of non-European descent. The 66-SNP blood pressure risk score was significantly associated with target organ damage in multiple tissues but with minor effects in the kidney. Our findings expand current knowledge of blood pressure-related pathways and highlight tissues beyond the classical renal system in blood pressure regulation.

Discovery and refinement of loci associated with lipid levels

Levels of low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides and total cholesterol are heritable, modifiable risk factors for coronary artery disease. To identify new loci and refine known loci influencing these lipids, we examined 188,577 individuals using genome-wide and custom genotyping arrays. We identify and annotate 157 loci associated with lipid levels at P < 5 × 10(-8), including 62 loci not previously associated with lipid levels in humans. Using dense genotyping in individuals of European, East Asian, South Asian and African ancestry, we narrow association signals in 12 loci. We find that loci associated with blood lipid levels are often associated with cardiovascular and metabolic traits, including coronary artery disease, type 2 diabetes, blood pressure, waist-hip ratio and body mass index. Our results demonstrate the value of using genetic data from individuals of diverse ancestry and provide insights into the biological mechanisms regulating blood lipids to guide future genetic, biological and therapeutic research.

The effect of vitamin D replacement on markers of vascular health in stroke patients - a randomised controlled trial

BACKGROUND AND AIMS

Low vitamin D levels are associated with increased incidence of future cardiovascular events and are common in stroke patients. We tested whether vitamin D supplementation could reduce blood pressure and improve markers of vascular health in patients who had previously suffered a stroke.

METHODS AND RESULTS

Randomised, placebo-controlled, double-blind trial. Community-dwelling patients with a history of stroke and baseline 25-hydroxyvitamin D levels <75 nmol/L received 100,000 units of oral vitamin D2 or placebo at baseline. Office and 24 h blood pressure, endothelial function measured by flow-mediated dilatation of the brachial artery, cholesterol, oxidised low density lipoprotein, B-type natriuretic peptide and heart rate turbulence were measured at baseline, 8 weeks and 16 weeks. 58 patients were randomised. Mean age was 67 years, mean baseline blood pressure 128/72 mmHg, mean baseline 25-hydroxyvitamin D level was 38 nmol/L. Serum 25-hydroxyvitamin D levels were higher in the intervention group at 8 weeks compared to placebo (54 vs 42 nmol/L, P = 0.002) and remained higher at 16 weeks. Office systolic and diastolic blood pressure showed no significant change between groups at 8 weeks (systolic 126.1 vs 131.3 mmHg; adjusted P = 0.97); (diastolic 73.1 vs 74.9 mmHg, adjusted P = 0.15). Flow mediated dilatation was significantly higher in the intervention group at 8 weeks (6.9% vs 3.7%, adjusted P = 0.007) but was not significantly different at 16 weeks.

CONCLUSIONS

High dose oral vitamin D supplementation did not improve blood pressure but produced short-term improvement in endothelial function in stroke patients with well-controlled baseline blood pressure.

CLINICAL TRIALS REGISTRATION

ISRCTN28737567.

Combined effect of inflammatory gene polymorphisms and the risk of ischemic stroke in a prospective cohort of subjects with type 2 diabetes: a Go-DARTS study

OBJECTIVE

We have previously observed that genetic profiles determined by the combination of five functionally significant single nucleotide polymorphisms (SNPs) (rs1800795, rs5498, rs5361, rs1024611, and rs679620) of genes encoding prototypical inflammatory molecules are associated with history of ischemic stroke. Here we tested the ability of this multigenic model to predict stroke risk in a large population-based prospective cohort of subjects with type 2 diabetes.

RESEARCH DESIGN AND METHODS

This study was conducted using a prospective cohort of individuals with type 2 diabetes participating in the Go-DARTS (Genetics of Diabetes Audit and Research in Tayside Scotland) study, which includes genetic and clinical information of patients with diabetes within the Tayside region of Scotland, U.K. The above-mentioned inflammatory SNPs were investigated in 2,182 Go-DARTS participants. We created an inflammatory risk score (IRS), ranging from 0 to 5, according to the number of "at-risk" genotypes concomitantly carried by a given individual. The primary outcome was the occurrence of fatal or nonfatal stroke of any kind. Mean follow-up time was 6.2 ± 1.1 years.

RESULTS

The incidence of stroke increased according to the IRS. The IRS was significantly and independently associated with increased stroke risk after adjustment for other conventional risk factors (hazard ratio 1.34 [95% CI 1.1-1.7]; P = 0.009). The highest hazard ratio for stroke was found in subjects concomitantly carrying > 3 proinflammatory variations and in subjects without previous cardiovascular diseases.

CONCLUSIONS

This large prospective cohort study provides evidence that SNPs of genes encoding prototypical inflammatory molecules may be used to create multigenic models that predict stroke risk in subjects with type 2 diabetes.

Reduced-function SLC22A1 polymorphisms encoding organic cation transporter 1 and glycemic response to metformin: a GoDARTS study

OBJECTIVE

Metformin is actively transported into the liver by the organic cation transporter (OCT)1 (encoded by SLC22A1). In 12 normoglycemic individuals, reduced-function variants in SLC22A1 were shown to decrease the ability of metformin to reduce glucose excursion in response to oral glucose. We assessed the effect of two common loss-of-function polymorphisms in SLC22A1 on metformin response in a large cohort of patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The Diabetes Audit and Research in Tayside Scotland (DARTS) database includes prescribing and biochemistry information and clinical phenotypes of all patients with diabetes within Tayside, Scotland, from 1992 onwards. R61C and 420del variants of SLC22A1 were genotyped in 3,450 patients with type 2 diabetes who were incident users of metformin. We assessed metformin response by modeling the maximum A1C reduction in 18 months after starting metformin and investigated whether a treatment target of A1C <7% was achieved. Sustained metformin effect on A1C between 6 and 42 months was also assessed, as was the time to metformin monotherapy failure. Covariates were SLC22A1 genotype, BMI, average drug dose, adherence, and creatinine clearance.

RESULTS

A total of 1,531 patients were identified with a definable metformin response. R61C and 420del variants did not affect the initial A1C reduction (P = 0.47 and P = 0.92, respectively), the chance of achieving a treatment target (P = 0.83 and P = 0.36), the average A1C on monotherapy up to 42 months (P = 0.44 and P = 0.75), or the hazard of monotherapy failure (P = 0.85 and P = 0.56).

CONCLUSIONS

The SLC22A1 loss-of-function variants, R61C and 420del, do not attenuate the A1C reduction achieved by metformin in patients with type 2 diabetes.