Acute glucosuria after continuous glucocorticoid loading in the rat in vivo

Pasireotide-induced hyperglycemia in a patient with Cushing's disease: Potential use of sodium-glucose cotransporter 2 inhibitor and glucagon-like peptide-1 receptor agonist for treatment

Pasireotide improves hypercortisolemia and induces hyperglycemia via somatostatin receptor type-5 stimulation. GLP-1RA and SGLT2 inhibitor potentially help regulate hyperglycemia in patients with Cushing's disease, especially after pasireotide administration.

Diabetes mellitus in chronic kidney disease: Biomarkers beyond HbA1c to estimate glycemic control and diabetes-dependent morbidity and mortality

Diabetes mellitus (DM) is the leading cause of chronic kidney disease (CKD). Optimal glycemic control contributes to improved outcomes in patients with DM, particularly for microvascular damage, but blood glucose levels are too variable to provide an accurate assessment and instead markers averaging long-term glycemic load are used. The most established glycemic biomarker of long-term glycemic control is HbA1c. Nevertheless, HbA1c has pitfalls that limit its accuracy to estimate glycemic control, including the presence of altered red blood cell survival, hemoglobin glycation and suboptimal performance of HbA1c assays. Alternative methods to evaluate glycemic control in patients with DM include glycated albumin, fructosamine, 1-5 anhydroglucitol, continuous glucose measurement, self-monitoring of blood glucose and random blood glucose concentration measurements. Accordingly, our aim was to review the advantages and pitfalls of these methods in the context of CKD.

Hemolysis causes a decrease in HbA1c level but not in glycated albumin or 1,5-anhydroglucitol level

HbA1c has been widely used as a glycemic control indicator or as a diagnostic indicator for diabetes mellitus. However, HbA1c is affected by the erythrocyte life span and, therefore, shows falsely low values in hemolytic patients. Erythrocyte creatine (EC) is a sensitive hemolytic marker that reflects the mean erythrocyte age. In the present study, the relationships of HbA1c, glycated albumin (GA), and 1,5-anhydroglucitol (1,5-AG) with different hemolytic markers, including EC, were investigated in non-diabetic individuals. A total of 43 non-diabetic individuals whose complete blood count and reticulocytes were measured via medical examinations were included in this study (28 individuals with hemolysis and 15 individuals without hemolysis). Those with suspected diabetes mellitus based on medical history, low 1,5-AG values, or had comorbid liver and renal diseases were excluded from this study. HbA1c, GA, 1,5-AG, and various hemolytic markers were measured to examine the correlation of the glycemic control indicators with the various hemolytic markers. A significant correlation was observed between GA and 1,5-AG but not between HbA1c and GA or 1,5-AG. Significant correlations were observed between HbA1c values and various hemolytic markers (reticulocytes, haptoglobin, and EC) but not between GA or 1,5-AG values and those hemolytic markers. HbA1c, but not with GA and 1,5-AG, showed significant correlations with the hemolytic markers. These results suggested that HbA1c does not reflect the glycemic control accurately in hemolytic patients, while GA and 1,5-AG values are not affected by mean erythrocyte age and, therefore, accurately reflect the glycemic control.

Basal glucosuria in cats

Objective of this study was to demonstrate the ubiquitous presence of glucose in urine of euglycemic cats by a highly sensitive glucose assay. The local electronic database was searched for results of quantitative urine glucose measurements in cats. A total of 325 feline urine glucose measurements were identified, of which 303 (93%) had been submitted by one of the co-authors working in a near-by small animal practice. After the exclusion of patients with kidney disease (n = 60), hyperthyroidism (n = 15), diabetes mellitus (n = 11), multiple diseases (n = 9) or steroid treatment (n = 3), as well as serial measurements (n = 87) and outliers (n = 8), the final study population consisted of 132 cats. Urine creatinine concentration was unavailable in five patients. Whereas all but one cat had glucose concentrations above the detection limit of the assay (0.11 mmol/L, Gluco-quant Enzyme Kit/Roche Diagnostics), no positive glucose dipstick test result (Combur 9-Test, Roche Diagnostics) was observed. The median (range) of urinary glucose concentration and the glucose-to-creatinine ratio (UGCR) was 0.389 (<0.11-1.665) mmol/L and 0.0258 (0.007-0.517) respectively. The UGCR was not affected by age, gender, breed or leukocyturia, whereas cats with hematuria had slightly higher values. Data show that so-called "basal glucosuria" is present in the majority of cats and by no means diagnostic for diabetes mellitus or renal glucosuria. This has to be considered when using bio-analytical methods with a low limit of quantification.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Glycated albumin is set lower in relation to plasma glucose levels in patients with Cushing's syndrome

BACKGROUND

Glycated albumin (GA) is an indicator of glycemic control, which has some specific characters in comparison with HbA1c. Since glucocorticoids (GC) promote protein catabolism including serum albumin, GC excess state would influence GA levels. We therefore investigated GA levels in patients with Cushing's syndrome.

METHODS

We studied 16 patients with Cushing's syndrome (8 patients had diabetes mellitus and the remaining 8 patients were non-diabetic). Thirty-two patients with type 2 diabetes mellitus and 32 non-diabetic subjects matched for age, sex and BMI were used as controls.

RESULTS

In the patients with Cushing's syndrome, GA was significantly correlated with HbA1c, but the regression line shifted downwards as compared with the controls. The GA/HbA1c ratio in the patients with Cushing's syndrome was also significantly lower than the controls. HbA1c in the non-diabetic patients with Cushing's syndrome was not different from the non-diabetic controls, whereas GA was significantly lower. In 7 patients with Cushing's syndrome who performed self-monitoring of blood glucose, the measured HbA1c was matched with HbA1c estimated from mean blood glucose, whereas the measured GA was significantly lower than the estimated GA.

CONCLUSIONS

We clarified that GA is set lower in relation to plasma glucose levels in patients with Cushing's syndrome.

A Pilot Study Comparing the Diabetogenic Effects of Dexamethasone and Prednisolone in Cats

Fourteen cats received either daily prednisolone (4.4 mg/kg per os [PO]) or dexamethasone (0.55 mg/kg PO) for 56 days. These doses were clinically equipotent. Serum fructosamine and urine glucose were measured on days 0, 28, and 56. Insulin sensitivity, glucose tolerance, and peak insulin secretion were measured in each group prior to and at the end of the courses of glucocorticoid administration. On day 56, the prevalence of glucosuria was significantly greater (P=0.027), and a trend was seen toward greater fructosamine concentrations (P=0.083) in dexamethasone-treated cats compared to prednisolone-treated cats. The results of this pilot study also showed a trend toward a greater decrease in insulin sensitivity (P=0.061) and a significantly lower compensatory increase in insulin secretion (P=0.081) in the dexamethasone-treated cats than in cats administered prednisolone. These preliminary data suggest that dexamethasone exhibits greater diabetogenic effects in cats than equipotent doses of prednisolone. Further study is justified to support this hypothesis.

Acute glucocorticoid treatment increases urinary biotin excretion and serum biotin

Previous studies have demonstrated that glucocorticoids alter biotin metabolism. To extend these studies, the effect of dexamethasone on biotin pools was analyzed in rats consuming a purified diet containing a more physiological level of dietary biotin intake (0.06 mg/kg). Acute (5 h) dexamethasone administration (0.5 mg/kg) elicited elevated urinary glucose output as well as elevated urinary biotin excretion and serum biotin. Renal and hepatic free biotin was also significantly elevated by acute dexamethasone administration. Chow-fed rats treated with an acute administration of dexamethasone demonstrated significantly elevated urinary glucose excretion, urinary biotin excretion, and serum biotin, but no change in tissue associated biotin was detected. Chronic administration of dexamethasone (0.5 mg/kg ip) over 4 days significantly elevated urinary glucose excretion 42% but had no effect on urinary biotin excretion, serum biotin, or hepatic- or renal-associated free biotin. These results demonstrate the existence of potentially novel regulatory pathways for total biotin pools and the possibility that experimental models with high initial biotin status may mask potentially important regulatory mechanisms.