Insulinopenia in impaired glucose tolerance preservation of insulin response to I.V. arginine and tolbutamide

The burden of anaemia in type 2 diabetes and the role of nephropathy: a cross-sectional audit

BACKGROUND

Anaemia is a common finding in patients with diabetes and constitutes an additional burden in patients with advancing age and comorbid vascular disease. This study examines the prevalence and predictors of anaemia in long-term outpatients with type 2 diabetes from three large clinical centres.

METHODS

A full blood count was obtained in addition to routine testing in a cross-sectional survey of all patients with type 2 diabetes in long-term follow-up at the Austin Medical Centre, Melbourne (n = 670) and the Royal Prince Alfred Hospital (n = 915) and the Royal North Shore Hospital (n = 540), Sydney, Australia. The prevalence and correlates of anaemia (haemoglobin < 130 g/l in men and < 120 g/l in women) were identified using multivariate logistic regression.

RESULTS

Roughly, one in five patients in each centre had anaemia. Patients at greatest risk could be readily identified by the presence of renal disease, manifested as impaired renal function and/or albuminuria in > 75% of patients with anaemia. Patients with diabetes and mild renal impairment [creatinine clearance (CCr) 60-90 ml/min/1.73 m(2)] were twice as likely to have anaemia as those with normal renal function (CCr > 90 ml/min/1.73 m(2)). Diabetics with moderate renal impairment (CCr < 60 ml/min/1.73 m(2)) were also twice as likely to have anaemia as those with mild renal impairment. Patients with anaemia were also more likely to have macrovascular disease, reflecting the high prevalence of nephropathy in these patients.

CONCLUSIONS

Anaemia is a prevalent finding in patients with type 2 diabetes and represents a significant unrecognized burden. Patients at greatest risk can be identified by the presence of renal disease, either in the form of renal impairment and/or albuminuria.

Taste impairment for glucose in diabetic PTC tasters and non-tasters

Effect of high blood glucose levels in diabetes mellitus was studied on gustatory responses to glucose in PTC tasters and non-tasters, before and after the ingestion of a glucose solution. After a 12-h overnight fast, prescreening for phenylthiocarbamide (PTC) sensitivity was done in each subject, and then each subject tasted, and rated, 7 concentrations of glucose solutions for intensity and hedonic responses. Blood glucose levels were also determined under fasting and then after a 100-g glucose load. A decrease in palatability of the glucose solutions induced by the glucose load (negative alliaesthesia) was evident in both groups of subjects. Tasters showed higher hedonic ratings (Mean 4-25), as compared to non-tasters (Mean 3-70) and this difference was more evident after the glucose load in non-tasters.

Effects of bezafibrate on insulin secretion and peripheral insulin sensitivity in hyperlipidemic patients with and without diabetes

Although it has been reported that bezafibrate influences carbohydrate metabolism, this possibility has never been properly evaluated in a controlled clinical trial. In this study we attempted to evaluate the effects of bezafibrate on plasma lipoproteins, glucose tolerance, insulin secretion and peripheral insulin sensitivity in a group of hypertriglyceridemic patients with and without diabetes. Sixteen hyperlipidemic patients (10 males and 6 females) participated in the study. Eight had type IIB and 8 type IV hyperlipoproteinemia; 6 of them also had non-insulin dependent diabetes mellitus. The study was performed according to a double blind, crossover design: after 1 month wash-out period in which patients were on diet alone, they underwent, in a random order, a period of placebo therapy and another period in which they received a single daily dose of a long-acting bezafibrate preparation (400 mg) administered in the evening. Each treatment lasted 2 months. Total plasma and VLDL triglyceride concentrations were consistently reduced by bezafibrate (-46%, P less than 0.001; and -50%, P less than 0.001). Total and VLDL-cholesterol were also reduced by bezafibrate. The effects of bezafibrate on lipoproteins were similar in diabetic and non-diabetic subjects. Bezafibrate treatment did not influence fasting blood glucose concentration, glucose tolerance, peripheral insulin sensitivity or insulin secretion. In conclusion, the results of this controlled trial clearly indicate that bezafibrate can be successfully employed to lower plasma lipid levels in patients with non-insulin dependent diabetes mellitus and hyperlipidemia.

Sensitivity to satiating and taste qualities of glucose in obese Zucker rats

A general "glucoreceptor" defect, demonstrable in pancreatic islet and taste cells, may contribute to the metabolic and taste abnormalities of adult onset diabetes and possibly, if present at the level of the hypothalamus, could produce hyperphagia and the obesity seen in diabetics. To determine if a glucoreceptor defect generally accompanies obesity and glucose intolerance, behavioral responsiveness to glucose was examined in nine obese and nine lean female Zucker rats. Daily food and fluid intake were measured during three two-bottle preference tests, in which rats chose between water and one of several glucose solutions (1%, 3%, and 12%). Taste responsiveness to glucose of obese rats appeared normal; however, increased satiating effects of glucose were found in obese rats, possibly due to an enhanced delivery of glucose to neurons that inhibit feeding, caused by glucose intolerance. Also, obese rats had (a) increased brain weights, and (b) increased volumes of ventromedial and paraventricular hypothalamic nuclei. These findings, perhaps explainable by an increased delivery of nutrients to the developing brain, indicate that the hyperphagia of Zucker rats is due neither to an overt hypothalamic lesion nor to insensitivity to glucose.