Angela A. Rivellese

Impact of postprandial glycaemia on health and prevention of disease.

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal‐related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Type of Dietary Fat and Insulin Resistance

Abstract: Animal studies have already shown the possibility to modulate insulin action by changing not only the amount of total fat, but also the type of fat. In these studies, saturated fat significantly increased insulin resistance, long‐ and short‐chain ω3 fatty acids significantly improved it, whereas the effects of monounsaturated and ω6 polyunsaturated fatty acids ranged somewhere in between the two. A recent multicenter study (the Kanwu study) on humans has shown that shifting from a diet rich in saturated fatty acids to one rich in monounsaturated fat improved insulin sensitivity in healthy people, while a moderate ω3 supplementation did not affect it; this second finding confirms previous results in type 2 diabetic patients with hypertriglyceridemia. There are also other aspects of the metabolic syndrome that can be influenced by the different type of dietary fat, particularly blood pressure and lipid metabolism. With respect to blood pressure, the majority of studies show that ω3 fatty acids are able to reduce blood pressure in hypertensive patients, but not in normotensive individuals; this result has been confirmed also by the Kanwu study, where no changes in blood pressure were seen after ω3 supplementation in healthy people. On the other hand, in this study, the change from saturated to monounsaturated fatty acids was able to significantly reduce diastolic blood pressure. As to the lipid abnormalities more frequently present in the metabolic syndrome (i.e., hypertriglyceridemia and low HDL cholesterol), the main effects are related to ω3 fatty acids, which surely reduce triglyceride levels, but at the same time increase LDL cholesterol. In conclusion, there is so far sound evidence in humans that the quality of dietary fat is able to influence insulin resistance and some of the related metabolic abnormalities.

Impaired glucose tolerance and risk factors for atherosclerosis.

This study attempts to evaluate whether the putative excess risk of cardiovascular disease in individuals with impaired glucose tolerance (IGT) can be explained by the clustering of other major cardiovascular risk factors after controlling for obesity. The study population was 1376 male and female employees of a Naples telephone company who had participated in a health survey in which an oral glucose tolerance test (OGTT) was given. After excluding treated hypertensives, we recruited all 65 individuals with IGT and 125 euglycemic controls matched for gender, age, and weight. Systolic and diastolic blood pressure was significantly higher in individuals with IGT (134 ± 16vs127 ± 15mmHg, p<0.001;87 ± 10vs84 ± 8 mm Hg, p < 0.05 (M ± SD). Blood lipids were similar in the two groups (total cholesterol was 214 ± 34vs218 ± 40 mg/dl; HDL cholesterol was 39 ± 9vs40 ± 10mg/dl; total triglyceride was 145 ± 58 vs 135 ± 63 mg/dl). Serum insulin values (fasting or at 1 or 2 hours after 75 g of oral glucose) were also similar. The number of persons currently smoking was significantly lower among individuals with IGT (30% vs 47%, p < 0.025) but the percentage of exsmokers was identical in the two groups. We conclude that, among the possible cardiovascular risk factors investigated, blood pressure is the only one significantly associated with IGT independent of matched variables and antihypertensive treatment.

Lipoprotein Composition in Individuals with Impaired Glucose Tolerance

The relationship between impaired glucose tolerance (IGT) and blood lipid levels was examined in 65 IGT individuals and in two control groups: control group I, composed of age-, sex-, and body weight-matched controls, and control group II, including normal subjects matched for sex and age but with normal body mass index. IGT individuals were found to have significantly higher total triglyceride (Tg) values compared with normal weight controls (P < 0.001), while no difference was found between IGT and control group I. Total cholesterol levels were similar in IGT and each of the control groups. No significant correlation was found between serum lipoproteins and blood glucose levels either fasting or after load.

Dietary Carbohydrates for Diabetics

The literature on the impact of dietary carbohydrates in the regulation of blood glucose levels and other metabolic abnormalities in diabetic patients over the last 3xa0years is reviewed. We try to differentiate the metabolic effects due to the amount of carbohydrates from those due to their different types. The review comprises a part dealing with the effects of diets having low or high carbohydrate content on body weight reduction, and a part in which the amount and the quality of carbohydrates are discussed in relation to isoenergetic diets. Overall, the data accumulated in the period considered seem to confirm that the decrease in energy intake is more important than the qualitative composition of the diet to reduce body weight, but that both the amount and the quality of carbohydrates are important in modulating blood glucose levels and other cardiovascular risk factors in both the fasting and the postprandial phases in diabetic individuals.

Mutilating fingertip ulcers in uncontrolled type 1 diabetes mellitus

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy in diabetic patients, which usually presents with the classic triad of nocturnal pain, hypoesthesia and thenar atrophy. Cutaneous involvement characterized by the appearance of ulcerative skin lesions, sclerodactylia, acro-osteolysis and mutilation is rare and occurs in patients with severe form of CTS [1]. A 39-year-old woman with poorly controlled type 1 diabetes mellitus developed painful blisters, subsequent ulcers and dystrophic modification of nails on the tips of the index and the middle finger of both hands over 8 weeks. In the following 7 months, ulcers complicated by osteomyelitis, which required antibiotic and hyperbaric oxygen therapy with little benefit (Fig. 1a, c). Radiological investigation disclosed a partial auto-amputation of the distal phalanx in the left index finger and an acro-osteolysis of the distal phalanx in the right index finger with a severe medullary bone edematous imbibition (Fig. 1b, d). Laboratory tests revealed a serum fasting glucose level of 16.67 mmol/l (300 mg/dl), increased haemoglobin A1c concentration: 92 mmol/mol (10.6 %). All other laboratory findings were normal, with no evidence of inflammatory or paraneoplastic syndrome, hemostatic disorder, thrombocytosis, thrombophilia, or monoclonal gammopathy, and levels of thyroid-stimulating hormone were normal. When she was referred to our institute, neurological examination showed bilateral atrophy of thenar muscles and severe loss of all sensory modalities in the median nerve territory. Tinel’s sign was positive bilaterally, and radiocubital arteries were permeable on Allen’s maneuver. Therefore, an entrapment syndrome of median nerve at carpal tunnel was supposed. The electrophysiological investigation showed no distal motor and sensory action potential in the median nerves and total denervation of the abductor pollicis brevis muscles, confirming the diagnosis of bilateral extreme CTS. Neurographic findings were normal in ulnar and lower limbs nerve (sural and tibial nerves). The patient underwent skin biopsy from third and fifth fingertip of right hand and processed according to published procedures [2]. At the third fingertip, innervated from median nerve, there was a complete skin denervation with the absence of Meissner corpuscles, epidermal nerve fibers and intrapapillary myelinated fibers. Denervation involved with the same severity the dermis leading to a complete disappearance of nerve fibers in the subepidermal neural plexus and around sweat glands and arteriovenous anastomoses. Moreover, sub-papillary vascular network was extremely complex with largely dilated vessels (Fig. 1f, h, j). In contrast, fifth fingertip skin biopsy, in the ulnar nerve territory, was normal (Fig. 1e, g, i). EchoR. Dubbioso F. Manganelli (&) Department of Neurological Sciences, University Federico II of Naples, Via Sergio Pansini, 5, 80131 Naples, Italy e-mail: fioremanganelli@gmail.com

Population diets influencing cardiovascular risk

The relationships between diet and cardiovascular disease are reviewed on the basis of the most important papers published during the past year. The review is divided into three parts: in the first, the relationships between dietary patterns and incidence of cardiovascular disease are reported; the second deals with the possibility of reversing even severe atherosclerosis by dietary change, and in the third section we consider the mechanisms by which diet may influence atherosclerosis.