Hypoxia can occur in pancreatic islets in type 2 diabetes mellitus. Pancreatic stellate cells (PSCs) are activated during hypoxia. Here we aimed to investigate whether PSCs within the islet are also activated in hypoxia, causing β-cell injury.
Islet and primary PSCs were isolated from Sprague Dawley rats, and cultured in normoxia (21% O2) or hypoxia (1% O2). The expression of α-smooth muscle actin (α-SMA), as measured by immunostaining and Western blotting, was used as a marker of PSC activation. Conditioned media (hypoxia-CM) were obtained from PSCs cultured in hypoxia.
Islets and PSCs cultured in hypoxia exhibited higher expressions of α-SMA than did those cultured in normoxia. Hypoxia increased the production of reactive oxygen species. The addition of N-acetyl-L-cysteine, an antioxidant, attenuated the hypoxia-induced PSC activation in islets and PSCs. Islets cultured in hypoxia-CM showed a decrease in cell viability and an increase in apoptosis.
PSCs within the islet are activated in hypoxia through oxidative stress and promote islet cell death, suggesting that hypoxia-induced PSC activation may contribute to β-cell loss in type 2 diabetes mellitus.
Citations
Whether pancreatic steatosis has a local or systemic effect, like ectopic fat of other major organs, remains unknown. Data on the influence of pancreatic steatosis on microvascular complication are rare. Therefore, we investigated the relationship between pancreatic steatosis and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).
The attenuation of three pancreatic regions (head, body, and tail) and the spleen (S) in 186 patients with T2DM was measured using non-enhanced computed tomography imaging. We used three parameters for the assessment of pancreatic steatosis (‘P’ mean: mean attenuation of three pancreatic regions; P–S: difference between ‘P’ mean and ‘S’; P/S: the ‘P’ mean to ‘S’ ratio). The presence of DR was assessed by an expert ophthalmologist using dilated fundoscopy.
The average P mean was 29.02 Hounsfield units (HU), P–S was −18.20 HU, and P/S was 0.61. The three pancreatic steatosis parameters were significantly associated with the prevalence of DR in non-obese T2DM patients. In the non-obese group, the odds ratios of P mean, P–S, and P/S for the prevalence of DR, after adjustment for age, sex, and glycosylated hemoglobin level, were 2.449 (
In this study, pancreatic steatosis was significantly associated with DR in non-obese patients with T2DM. Further studies are necessary to clarify the causal relationship between pancreatic steatosis and the development of DR.
Citations
We investigated clinical course and risk factors for diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).
A total of 759 patients with T2DM without DR were included from January 2001 to December 2004. Retinopathy evaluation was performed at least annually by ophthalmologists. The severity of the DR was classified into five categories according to the International Clinical Diabetic Retinopathy Severity Scales.
Of the 759 patients, 523 patients (68.9%) completed the follow-up evaluation. During the follow-up period, 235 patients (44.9%) developed DR, and 32 patients (13.6%) progressed to severe nonproliferative DR (NPDR) or proliferative DR (PDR). The mean duration of diabetes at the first diagnosis of mild NPDR, moderate NPDR, and severe NPDR or PDR were 14.8, 16.7, and 17.3 years, respectively. After adjusting multiple confounding factors, the significant risk factors for the incidence of DR risk in patients with T2DM were old age, longer duration of diabetes, higher mean glycosylated hemoglobin (HbA1c), and albuminuria. Even in the patients who had been diagnosed with diabetes for longer than 10 years at baseline, a decrease in HbA1c led to a significant reduction in the risk of developing DR (hazard ratio, 0.73 per 1% HbA1c decrement; 95% confidence interval, 0.58 to 0.91;
This prospective cohort study demonstrates that glycemic control, diabetes duration, age, and albuminuria are important risk factors for the development of DR. More aggressive retinal screening for T2DM patients diagnosed with DR should be required in order to not miss rapid progression of DR.
Citations
We investigated an association between baseline heart rate-corrected QT (QTc) interval before severe hypoglycemia (SH) and prolongation of QTc interval during SH in patients with type 2 diabetes mellitus (T2DM).
Between January 2004 and June 2014, 208 patients with T2DM, who visited the emergency department because of SH and underwent standard 12-lead electrocardiography within the 6-month period before SH were consecutively enrolled. The QTc interval was analyzed during the incidence of SH, and 6 months before and after SH. QTc intervals of 450 ms or longer in men and 460 ms or longer in women were considered abnormally prolonged.
The mean age and diabetes duration were 68.1±12.1 and 14.1±10.1 years, respectively. The mean QTc intervals at baseline and SH episodes were 433±33 and 460±33 ms, respectively (
A prolonged QTc interval at baseline was significantly associated with prolongation of the QTc interval during SH in patients with T2DM, suggesting the necessity of QTc interval monitoring and attention to those with a prolonged QTc interval to prevent SH.
Citations
Some patients with type 2 diabetes mellitus (T2DM) do not develop diabetic kidney disease (DKD) despite the presence of advanced diabetic retinopathy (DR). We aimed to investigate the presence of DKD and its risk factors in patients with T2DM and advanced DR.
We conducted a cross-sectional study in 317 patients with T2DM and advanced DR. The phenotypes of DKD were divided into three groups according to the urine albumin/creatinine ratio (uACR, mg/g) and estimated glomerular filtration rate (eGFR, mL/min/1.73 m2): no DKD (uACR <30 and eGFR ≥60), non-severe DKD (uACR ≥30 or eGFR <60), and severe DKD (uACR ≥30 and eGFR <60). Mean systolic and diastolic blood pressure, mean glycosylated hemoglobin (HbA1c) level, and HbA1c variability (standard deviation [SD] of serial HbA1c values or HbA1c-SD) were calculated for the preceding 2 years.
The prevalence of no DKD, non-severe DKD, and severe DKD was 37.2% (
The prevalence of DKD was about 60% in patients with T2DM and advanced DR. HbA1c variability and TG/HDL-C ratio may affect the development and progression of DKD in these patients.
Citations
We investigated the association between severe hypoglycemia (SH) and the risk of cardiovascular (CV) or all-cause mortality in patients with type 2 diabetes.
The study included 1,260 patients aged 25 to 75 years with type 2 diabetes from the Vincent Type 2 Diabetes Resgistry (VDR), who consecutively enrolled (
Among the 906 participants (71.9%) who completed follow-up, 85 patients (9.4%) had at least one episode of SH, and 86 patients (9.5%) died (9.1 per 1,000 patient-years). Patients who had died were older, had a longer duration of diabetes and hypertension, received more insulin, and had more diabetic microvascular complications at baseline, as compared with surviving patients. The experience of SH was significantly associated with an increased risk of all-cause mortality (hazard ratio [HR], 2.64; 95% confidence interval [CI], 1.39 to 5.02;
We found a strong association between SH and increased risk of all-cause and CV mortality in patients with type 2 diabetes.
Citations
Predictors of Diabetes Self-Care Practice Among Patients with Type 2 Diabetes in Public Hospitals in Northeastern Ethiopia: A Facility-Based Cross-Sectional Study
To investigate whether a history of prior cardiovascular disease (CVD) is associated with severe hypoglycemia (SH) in patients with type 2 diabetes.
We conducted a prospective cohort study from January 2001 to December 2012 with a median follow-up time of 9.5 years (5,814 person-years). Patients aged 25 to 75 years with type 2 diabetes and without chronic kidney disease were enrolled (
Among the 624 participants who completed follow-up, 60 patients (9.6%) had previous CVD. Compared to patients without CVD, patients with previous CVD were older, had a longer duration of diabetes and hypertension, received more insulin, and had more diabetic microvascular complications at baseline. During follow-up, 62 patients (9.9%) experienced at least one SH episode (incidence of 1.33 per 100 patient-years). The development of SH was associated with a history of CVD (hazard ratio, 1.99; 95% confidence interval, 1.07 to 3.72;
A history of CVD was an independent risk factor for the development of SH in patients with type 2 diabetes mellitus. For patients with CVD, modulation of glycemic targets and diabetic education for the prevention of hypoglycemia should be implemented.
Citations
The aim of this study was to investigate the influences of visceral adiposity on cardiovascular autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus.
Two hundred eleven patients with type 2 diabetes participated in this study. Anthropometric and metabolic parameters were measured, and the visceral fat area was assessed using computed tomography. CAN was diagnosed using a cardiovascular reflex test. We analyzed the correlation between the visceral fat area and each parameter in this test.
The mean age, body mass index (BMI), and duration of diabetes of the study population were 60±14 years (mean±standard deviation), 25.1±4.2 kg/m2, and 12.3±8.9 years, respectively. The visceral fat area showed positive correlations with age, BMI, waist circumference, and subcutaneous fat area. There was no statistically significant difference in the cardiovascular reflex test outcome between genders. Univariate linear regression analysis showed that an increased visceral fat area diminished good heart rate response to a Valsalva maneuver (
The results of this study suggest that visceral adiposity contributes to an autonomic imbalance to some degree, as demonstrated by the impaired cardiovascular reflex test among women with type 2 diabetes.
Citations
Diabetes education and lifestyle modification are critical components in controlling blood glucose levels of people with type 2 diabetes. Until now, available data on the effectiveness of education with respect to the duration of diabetes are limited. We investigated whether adherence to lifestyle behavior modification prompted by diabetes education was influenced by the duration of diabetes.
Two hundred and twenty-five people with type 2 diabetes were recruited for an intensive, collaborative, group-based diabetes education program with annual reinforcement. We divided the patients into two groups based on the duration of their diabetes prior to the education program (≤1 year [≤1Y] vs. ≥3 years [≥3Y]). Dietary habits, physical activity, and the frequency of blood glucose self-monitoring were evaluated with a questionnaire prior to education and at the follow-up endpoint.
The mean follow-up period was 32.2 months. The mean hemoglobin A1c (A1C) value was significantly lower in the ≤1Y group. Self-care behaviors, measured by scores for dietary habits (
Diabetes duration influenced the effectiveness of diabetes education on lifestyle behavior modification and glycemic control. More-intense, regular, and sustained reinforcement with encouragement may be required for individuals with longstanding type 2 diabetes.
Citations
Glucose toxicity that is caused by chronic exposure to a high glucose concentration leads to islet dysfunction and induces apoptosis in pancreatic β-cells. Heme oxygenase-1 (HO-1) has been identified as an anti-apoptotic and cytoprotective gene. The purpose of this study is to investigate whether HO-1 up-regulation when using metalloprotophyrin (cobalt protoporphyrin, CoPP) could protect pancreatic β-cells from high glucose-induced apoptosis.
Reverse transcription-polymerase chain reaction was performed to analyze the CoPP-induced mRNA expression of HO-1. Cell viability of INS-1 cells cultured in the presence of CoPP was examined by acridine orange/propidium iodide staining. The generation of intracellular reactive oxygen species (ROS) was measured using flow cytometry. Glucose stimulated insulin secretion (GSIS) was determined following incubation with CoPP in different glucose concentrations.
CoPP increased HO-1 mRNA expression in both a dose- and time-dependent manner. Overexpression of HO-1 inhibited caspase-3, and the number of dead cells in the presence of CoPP was significantly decreased when exposed to high glucose conditions (HG). CoPP also decreased the generation of intracellular ROS by 50% during 72 hours of culture with HG. However, decreased GSIS was not recovered even in the presence of CoPP.
Our data suggest that CoPP-induced HO-1 up-regulation results in protection from high glucose-induced apoptosis in INS-1 cells; however, glucose stimulated insulin secretion is not restored.
Citations
Type 2 diabetes mellitus (T2DM) is often accompanied by increased levels of circulating fatty acid. Elevations in fatty acids and glucose for prolonged periods of time have been suggested to cause progressive dysfunction or apoptosis of pancreatic beta cells in T2DM. However, the precise mechanism of this adverse effect is not well understood.
INS-1 rat-derived insulin-secreting cells were exposed to 30 mM glucose and 0.25 mM palmitate for 48 hours.
The production of reactive oxygen species increased significantly. Pancreatic and duodenal homeobox 1 (Pdx1) expression was down-regulated, as assessed by reverse transcription-polymerase chain reaction and Western blot analyses. The promoter activities of insulin and Pdx1 were also diminished. Of note, there was nucleocytoplasmic translocation of Pdx1, which was partially prevented by treatment with an antioxidant, N-acetyl-L-cysteine.
Our data suggest that prolonged exposure of beta cells to elevated levels of glucose and palmitate negatively affects Pdx1 expression via oxidative stress.
Citations