Chlorpropamide-alcohol flushing and proteinuria in non-insulin-dependent diabetics

[Fundamental Properties of Aldehyde Dehydrogenase 2 (ALDH2) and the Importance of the ALDH2 Polymorphism]

Human aldehyde dehydrogenase 2 (ALDH2) is a 56 kDa mitochondrial protein that forms homodimers through hydrogen bonding interactions between the Glu487 and Arg475 residues of two ALDH2 proteins. Two ALDH2 homodimers can interact to form an ALDH2 tetramer. ALDH2 is widely distributed throughout the organs of the body. In addition to its dehydrogenase activity, ALDH2 also exhibits esterase and reductase activities, with the main substrates for these three activities being aldehydes, 4-nitrophenyl acetate and nitroglycerin, respectively. ALDH2 can be readily inhibited by a wide variety of endogenous and exogenous chemicals, but the induction or activation of this enzyme remains unlikely. The polymorphism of ALDH2 to the corresponding ALDH2*2 variant results in a severe deficiency in ALDH2 activity, and this particular polymorphism is prevalent among people of Mongoloid descent. It seems reasonable to expect that people with the ALDH2*2 variant would be more vulnerable to stress and diseases because ALDH2 defends the human body against toxic aldehydes. However, it has been suggested that people with the ALDH2*2 variant are protected by alternative stress-defending systems. The ALDH2*2 variant has been reported to be associated with many different kinds of diseases, although the mechanisms underlying these associations have not yet been elucidated. ALDH2 polymorphism has a significant impact on human health; further studies are therefore required to determine the practical implications of this polymorphism in the fields of preventive and clinical medicine.

Facial skin temperature in chlorpropamide alcohol flush

Objective methods to study the chlorpropamide alcohol flush (CPAF) have been inadequate. Determination of blood acetaldehyde has proved to be a promising method, but the analysis is difficult and time-consuming. To measure the facial skin temperature is more handy. The results of these measurements can be presented as delta T (skin temperature increase), %T (per cent of maximum possible temperature rise) or delta MTCI (malar thermal circulation index) after calculations. The baseline skin temperature is accounted for in %T and delta MTCI. Blood acetaldehyde determinations and placebo-alcohol tests can be used to separate the CPAF reaction from alcohol flushing. Single dose CPAF tests including facial skin temperature measurements were performed in 133 type 2 (non-insulin dependent) diabetics. Facial flush was observed in 42.9%. The specificity and sensitivity of all three skin temperature methods were high: 88.2, 85.5, 96.1%, and 89.5, 86.0, 86.0%, respectively. Skin temperature measurement, whether expressed as delta T, %T or delta MTCI, provides a method to study CPAF with high accuracy.

Alcohol and treatment of diabetes

The effects of alcohol on diabetic patients controlled on insulin are reviewed and the associated risks of hypoglycaemia, insulin resistance and ketosis are commented on. The impact of alcohol intake in patients with maturity onset diabetes is also considered and potential interactions with oral hypoglycaemic agents highlighted.

Genetic and metabolic risk factors for the development of late complications in type I (insulin-dependent) diabetes

The genetic background seems to be involved in the development of type I diabetes and it might also be involved in the development of diabetic complications, but studies carried out so far have yielded conflicting results. The aim of this study was to evaluate the influence of some genetic markers and metabolic factors in the development of late diabetic complications. One hundred and twenty-seven patients (69 males, 58 females) with type I diabetes were evaluated for ABO and Rh blood groups, chlorpropamide alcohol flush (CPAF) and acetylator phenotype (AP) as well as for life-habits (smoking, alcohol use, diet and drug compliance), metabolic indexes (M-value, HbA1, cholesterol and triglyceride levels) and late complications of diabetes [coronary heart disease (CHD), arterial hypertension (AH), retinopathy and nephropathy]. Diabetic patients were more frequently fast acetylators and CPAF positive than controls and CPAF was more frequent among females than among males. None of the genetic markers used in this study appeared as a risk factor for the development of diabetic complications. At multiple logistic analysis different risk factors appeared for each microangiopathic complication. For retinopathy: female sex, duration of disease and triglyceride levels; for nephropathy: male sex, cholesterol levels and hypertension. These risk factors have already been recognized in previous studies, while the genetic markers evaluated in our study do not identify a greater or smaller risk for the development of late complications.

[Facial vasomotor flushing due to alcohol-chlorpropamide. Prevalence in diabetic and non-diabetic patients]

Using a standard test (sherry 40 ml 12 hours and 36 hours after 250 mg chlorpropamide), chlorpropamide-alcohol flush (CPAF) prevalence was 34 p. 100 (19/56) in non insulin-dependent diabetics (NIDD), 10 p. 100 (3/30) in insulin-dependent diabetics and 7 p. 100 (2/27) in controls. Family history of diabetes was not associated with CPAF trait. Conflicting results in the literature might be explained by bias in patients selection or methodology.

Chlorpropamide-alcohol flush: significance of body weight, sex and serum chlorpropamide level

Chlorpropamide-alcohol flush (CPAF) tests were carried out in 15 male and 15 female Type 2 diabetics. Twelve subjects were CPAF-positive and 18 were -negative. The two groups did not differ in age or duration of diabetes, but the CPAF-positive subjects weighed less (mean difference 13 kg) and had higher plasma chlorpropamide levels. There was a negative correlation between plasma chlorpropamide and body weight, and a positive correlation between plasma chlorpropamide and the increase in facial skin temperature. Females had higher plasma chlorpropamide, a greater skin temperature increase and lower body weight than males; there were 11 females and only 1 male amongst the 12 CPAF-positive subjects. The findings confirm that plasma chlorpropamide is a major determinant of the CPAF reaction and also show that body weight strongly influences the chlorpropamide level and, consequently, the outcome of the CPAF test. The sex difference in body weight probably accounts for most, if not all, of the sex difference in the incidence of the CPAF.

Metabolic studies in chlorpropamide-alcohol flush positive and negative Type 2 (non-insulin dependent) diabetic patients with and without retinopathy

Serum insulin and blood metabolite responses to oral glucose with and without intravenous naloxone were measured in 24 chlorpropamide-alcohol flush positive and negative Type 2 (non-insulin dependent) diabetic patients with and without retinopathy. In the chlorpropamide-alcohol flush positive patients with retinopathy, fasting blood glucose was increased greater than 40% and the serum triglycerides were increased over twofold compared with each of the other three groups. Following oral glucose (50 g), the chlorpropamide-alcohol flush positive diabetic patients with complications had a lower serum insulin and higher blood glycerol than the other three groups. Thus, chlorpropamide-alcohol flush positive subjects with retinopathy showed distinct metabolic differences from the other three groups. There was no evidence that opiate-receptors influenced the metabolic response to oral glucose in the Type 2 diabetic patients since the infusion of intravenous naloxone produced no effect on the serum insulin or blood metabolites.

Plasma chlorpropamide: a critical factor in chlorpropamide-alcohol flush

The chlorpropamide-alcohol flush (CPAF) phenomenon was quantitatively related to blood levels of acetaldehyde and chlorpropamide in 105 Type II diabetics, of whom 74 had not previously taken the drug and 31 were on chronic treatment. Standardized skin temperature recordings were made with a sensitive probe. Plasma ethanol and acetaldehyde concentrations were determined by gas chromatography, and those of chlorpropamide by high-pressure liquid chromatography. There were significant positive correlations between plasma acetaldehyde and the skin temperature increase, between plasma chlorpropamide and plasma acetaldehyde, and between plasma chlorpropamide and the skin temperature increase. CPAF-positive patients became CPAF-negative and vice versa following reduction and increase, respectively, in the dose of chlorpropamide. Thus, the CPAF reaction is a consequence of chlorpropamide inhibition of the oxidation of ethanol-generated acetaldehyde, and it appears that the plasma concentration of chlorpropamide is critical. It remains an open question whether the CPAF test has any prognostic value.

Chlorpropamide-alcohol flushing, aldehyde dehydrogenase activity, and diabetic complications

Many diabetics who take chlorpropamide (a sulphonylurea compound) experience facial flushing after drinking even small amounts of alcohol. These flushers have a noticeably lower prevalence of late complications of diabetes (microangiopathy, macroangiopathy, and neuropathy) than non-flushers. This flush reaction is accompanied by increased blood acetaldehyde concentrations, suggesting an inhibition of aldehyde dehydrogenase activity. In the present study the activity of this enzyme in erythrocytes was assessed in the absence of chlorpropamide. Erythrocyte homogenates obtained from flushers and non-flushers were incubated with acetaldehyde and the rate of metabolism studies. Flushers eliminated acetaldehyde more slowly at a low range of concentrations (0--30 mumol/l), suggesting a difference in aldehyde dehydrogenase activity. Further studies are needed to clarify the role of this enzyme in the pathogenesis of diabetic complications.