Background: For people with type 1 diabetes, there is no alternative to treatment with insulin. The major side effect of insulin is severe hypoglycaemia (SH), when the patient needs help or even becomes unconscious. Material: We have studied a geographic population of yearly 130-140 unselected type 1 diabetes patients aged 1-18 years during 1992-1999. They were intensively treated with 87-96% on 4-7 daily insulin doses, combined with active self-control, psychosocial support and problem-based education from onset. Average HbA1c was 6.5 with Mono-S standard (1.15% beow DCCT level). Methods: We evaluated use of a prospective patient questionnaire for continuous long-term registration of treatment and outcome data and analysed HbA1c, SH and other variables. Over years, 95-100% response rate was achieved. We used also temporary questionnaries. Results: We found SH with unconsciousness reported from on average 11% of patients yearly, SH without unconsciousness but needing assistance from on average 36% yearly and weak associations to HbA1c, such as reletive risk of SH 1.24 for yearly mean HbA1c <7.0% compared to ≥7.0% There was a seasonal variation in HbA1c (p=0.023) and incidence of SH. The strongest predictor for SH was SH during the previous year (r=9.38, p<0.0001). The impact from SH showed great variation, and 20-30% of events led to practical disturbancies for parents and/or other people. Hospital visits took place only at 5% and hospitalisations at 3% of events. Social activities for patients were cancelled after 10% of events. Increased worry for patients was reported after 8% of events, bad sleep after 7%. We estimated the average socio-economic cost for SH at EURO 239 per event of SH with unconsciousness, and EURO 63 per event of SH without unconsciousness but needing assistance. Mass-distributed self-study material (brochures and videos) aimed at the prevention of SH without compromising metabolic control reached high dissemination and was widely appreciated by patients. The material copy cost was only EURO 7 per patient. It also seems to have contributed to a decrease in SH with unconsciousness from yearly 13% of patients before to 9% after intervention (3-years average), but controlled studies are needed. Conclusions: We conclude that SH remains a very serious problem of multifactorial aethiology. It causes considerable discomfort and costs. Systematic patient education mgiht reduce the incidence. Interventions using mass-distribution of high quality self-study material such as videos and brochures seem to have a potential to be cost-effective. There is a great patient/consumer interest in high quality- and advanced information/education materials.

Thesis (M. Sc. (Biochemistry)) -- University of Limpopo, 2015 / Diabetes mellitus is one of the major diseases worldwide that is life threatening and is reaching an epidemic proportion. The most important approach in reducing the burden of the disease worldwide is to search for effective, low cost hypoglycaemic drugs with fewer side effects. Past experimental evidence confirmed the hypoglycemic activity of many indigenous African medicinal plants. S. italica (Fabaceae family) is widely used by traditional healers to treat a number of diseases such as sexually transmitted diseases and other forms of intestinal complications traditionally. The current study was aimed at evaluating the in vitro effects of root and leaf extracts of S. italica on GLUT4 translocation in NIH-3T3-L1 preadipocytes and C2C12 muscle cells. In order to address the aim of the study various methods were undertaken. The roots and leaves of S. italica collected from Zebediela sub-region of the Limpopo province, South Africa, were ground to fine powder and extracted using acetone, methanol, ethyl acetate and n-hexane. The various extracts of the root and leaf material were subjected to fingerprint profiling using TLC plates and different mobile phases (BEA, CEF, EMW and BAW). The chromatograms were visualized with vanillin-H2SO4 reagent, p-anisaldehyde and iodine vapour. The extracts were assayed for the type of secondary metabolites contained in the studied plant parts using chemical text and by TLC analysis. The total phenolic content of the root and leaf material were also evaluated. Evaluation for antioxidant activity was performed using 0.2% DPPH qualitatively and quantitatively with vitamin C as a positive control. Toxicity study was performed on C2C12 muscle cells using the MTT assay, with Curcumin as a positive control and untreated cells as a negative control. The CC50 values of the acetone root and leaf extracts were determined by linear regression. The effect of acetone root and leaf extracts on glucose uptake by C2C12 muscle cells was evaluated, also on western blot and immunofluorescence for NIH-3T3-L1 preadipocytes. The solvents employed for extraction in this study are commonly used to extract various biological active compounds from plants in research settings. Methanol extracted more compounds followed by acetone, then ethyl acetate and n-hexane the least. The constituents extracted by methanol may be mostly sugars, amino acids and glycosides due to the polarity of this solvent. Hydro-alcoholic solvents extract a variety of compounds that are mostly polar. Acetone extracts mostly alkaloids, aglycones and glycosides while n-hexane in general extracts mostly waxes, fats and fixed oils. High yield was obtained with leaf extracts with all the solvent used for extraction as compared to the root. The TLC finger-print showed that good separation was achieved with the methanol and acetone extracts in CEF mobile phase, ethyl acetate extracts in CEF and EMW and n-hexane extracts in BEA respectively, especially with the leaf extract. Most compounds present in S. italica extracts were UV active. Some compounds that were not reactive with vanillin-H2SO4 reagent were shown to be reactive with p-anisaldehyde reagent and iodine vapour which revealed the presence of sugars or aromatic compounds. Chemical analysis for secondary metabolites of the acetone root and leaf extracts revealed the presence of flavonoids, terpenes, tannins, steroids, reducing sugars and alkaloids while glycosides were detected only in the leaf extract. The results obtained using TLC analyses were consistent with the results obtained in the chemical analysis. Thin layer chromatography revealed the presence of glycoflavones in the acetone root extract, alkaloids in the root and leaf extracts; and phytosterols and flavonoid aglycones in root and leaf extracts. The acetone root and leaf extracts revealed the presence of phenols. The leaf extract was shown to contain high total phenolic content as compared to the root. The methanol and acetone root and leaf extracts were shown to possess antioxidant activity. However, the concentration of the activity was higher in the acetone root than in the leaf extract. The least activity was observed with the ethyl acetate root and leaf extracts as compared to other extracts. The n-hexane extracts however, was not shown to contain any antioxidant compounds. Although activity observed with the methanol extracts was comparable to that of the acetone extracts in the quantitative assay, the acetone extracts were shown to possess more antioxidant activity in the qualitative assay. The concentration of extracts increased with increase in scavenging activity. The root extract exhibited a more potent antioxidant activity compared to leaf extract. These extracts were evaluated for their cytotoxicity on normal cells. The highest cytotoxic concentration (CC50) was obtained with the root extract with a CC50 value of 297 635 μg/ml at 48 hrs, followed by CC50 value of 21 544 μg/ml at 24 hrs. The CC50 value of the leaf extract at 24 hrs was 2 904 μg/ml with the least value at 48 hrs. The root extract at 24 and 48 hrs together with the leaf extract at 24 hrs were not toxic to C2C12 muscle cells at the concentration tested in this study. The acetone extracts were shown to possibly enhance proliferation of C2C12 muscle cells at a concentration of 0.001–1000 μg/ml. The non-cytotoxic concentration of 25 μg/ml of the leaf extract in combination with insulin showed more glucose uptake as compared to other extracts as well as the control. Prolonged incubation time was shown to increase glucose uptake with leaf extract while increase in concentration of root extract decreased glucose uptake at 24 hrs. At incubation time of 3 and 24 hrs, glucose uptake results at concentration of 2.5 μg/ml were comparable with that of the root extract, with a similar trend observed at 25 μg/ml, although with decrease in uptake. The qualitative and quantitative fluorescence results showed GLUT4 to be translocated to the cell membrane. The leaf extract at a concentration of 25 μg/ml had more fold as compared to other extracts, indicative that more GLUT4 was translocated at this concentration of the leaf extract. The acetone root and leaf extracts were shown to increase protein expression of GLUT4 at 3 hrs incubation time as compared to other incubation times in insulin-stimulated C2C12 muscle cells. The plant constituents of S. italica was shown to contain a variety of secondary metabolites that maybe be acting alone or in concert with each other to exert the various activities observed in this study. Different solvents used for extraction may be responsible for the extraction of different constituents with antioxidant activity observed in the study. The acetone extracts enhanced proliferation of C2C12 muscle cells at concentrations used in the study. However, there was no significant reduction on viability of normal cells. In addition, the extracts were shown to enhance the differentiation of NIH-3T3-L1 preadipocytes into adipocytes and C2C12 muscle cells into myocytes. These in turn induced the translocation of GLUT4 to the cell membrane and as a consequence facilitate glucose transport. Hence, the differentiation of adipose cells as well as glucose uptake of muscle cells and GLUT4 expression might have been enhanced by constituents contained in the acetone extracts. In conclusion, the acetone leaf extract may have a beneficial role in glucose metabolism of differentiated C2C12 muscle cells. Therefore, further studies are however required to elucidate the molecular mechanism by which the acetone leaf extract of S. italica influences the translocation of GLUT4.

Thesis (MNutr (Interdisciplinary Health Sciences. Human Nutrition))--University of Stellenbosch, 2008. / BACKGROUND: Although hypoglycaemia is a known complication of haemodialysis, there is little information about its prevalence among patients on maintenance haemodialysis. OBJECTIVE: To determine the prevalence of hypoglycaemia in patients on maintenance haemodialysis in Kenyatta National Hospital (Nairobi, Kenya) and to identify potential nutritionrelated causes of hypoglycaemia. METHODS: A cross-sectional, descriptive and observational study design was followed. Patients who had been on chronic maintenance haemodialysis for 3 months or longer were included in the study which was carried out from May 8 through to June 30, 2006. Random blood glucose levels were determined at baseline, 15 minutes, 30 minutes and 45 minutes, and at hourly intervals thereafter until the end of the dialysis session. The prevalence of hypoglycaemia (a blood glucose level less than 3.9 mmol/L) was then determined for the duration of haemodialysis. The relationship between minimum blood glucose levels and dietary intake, anthropometric status, primary diagnosis, co-morbid and socio-demographic factors, prescribed medication and dialysis related factors was determined. RESULTS: Among the 51 haemodialysis patients who participated in the study, the prevalence of hypoglycaemia was 16% (n=8). Eight percent (n=4) of these patients were however already hypoglycaemic on initiation of dialysis. Dietary intake of niacin ((r=0.31; p=0.02), riboflavin (r=0.30; p=0.03) and vitamin B6 (r=0.30; p=0.03) showed a significant relationship with blood glucose levels. The relationships between hypoglycaemic episodes and insulin administration (p=0.06), and between blood glucose levels and BMI (r=0.25; p=0.08 and protein intake (r=0.26; p=0.07) approached significance. There was no significant relationship between blood glucose levels and the duration of haemodialysis (p=0.942), hours of haemodialysis (p=0.27) and the dialysate solution used (p=0.12). CONCLUSIONS: Hypoglycaemia was present in 16% of patients on maintenance haemodialysis. Potential nutritional parameters which may have contributed to lower blood glucose levels in this study include a lower dietary intake of niacin, riboflavin, and vitamin B6. Lower protein intake and lower BMI was marginally associated with low blood glucose levels.

Diabetes is a rapidly growing health concern in the developed world. Hypoglycaemia is a major risk factor in people with diabetes. Each year, about 7000 calls relating to hypoglycaemia are made to the Scottish Ambulance Service (SAS), including a considerable number of repeat callers. Very little is known about people’s experiences and explanations of recurrent hypoglycaemia; in particular, why some individuals manage their recurrent hypoglycaemic episodes independently, while others require more direct healthcare support. This thesis investigated participants’ experiences and individual explanations of recurrent hypoglycaemic episodes, in order to understand their health help-seeking behaviour. To do this, it compared the experiences of people who had called the emergency services within one month prior to recruitment (SAS participants), with those people who had not done so (non-SAS participants). The study employed a multiple methods longitudinal approach to prospectively capture participants’ experiences of hypoglycaemic episodes, using qualitative semi-structured interviews, hypoglycaemia and blood glucose diaries and follow-up telephone interviews over a six month period. Thirty participants were involved in the study, recruited through the Scottish Ambulance Service, Diabetes UK (Scotland), and the University of Stirling. All participants resided in the central belt of Scotland. Qualitative data was analysed using the framework method, and quantitative data was analysed using descriptive statistics. This study found that hypoglycaemic episodes had a wide ranging impact on people’s everyday life. It was not only the actual hypoglycaemic episode that affected participants’ everyday life, but also fears and worries about future hypoglycaemic episodes, the preparations that participants engaged in, and the process of recovery. Hypoglycaemia unawareness was found to be a major problem for many people living with diabetes. It appeared to be associated with the likelihood of needing external help. There were differences between participant groups with regard to management of hypoglycaemia unawareness. Non-SAS participants adopted strategies to prepare for future hypoglycaemic episodes, and appeared to be more knowledgeable about their diabetes and its management, resulting in needing less external help. SAS participants experienced more severe hypoglycaemic episodes. Consequently, they relied more on external help. Findings of this study call for a re-conceptualisation of the previously recognised ‘balancing act’ of managing diabetes and hypoglycaemic episodes. This study introduces the concept of a hypoglycaemic episode balancing continuum (HEBC) which enables a deeper understanding of the factors involved in this balancing act: it demonstrates that people balance the various risks differently, depending on whether they prioritised their fear of hypoglycaemia over fears of long-term complications. People’s position on the continuum directly affected their management strategies for hypoglycaemic episodes. Most hypoglycaemic episodes were managed by the individual without requiring any external help. However, participants’ ability to self-care differed and deficits occurred, resulting in participants being more likely to need involvement of others (family/friends). When the capacity of others to help broke down, participants’ were more likely to need SAS emergency care. In order to explain how hypoglycaemic episodes are managed, this thesis has developed a hypoglycaemic episode help-seeking network (HEHS network), which helps to identify the various agents involved in helping to manage hypoglycaemic episodes. Findings from this study have implications for clinical practice. For example, looking at hypoglycaemia unawareness, this study has shown that current understanding may fail to take account of participants’ real experiences, which show hypoglycaemia unawareness to be a fluid phenomenon that can affect people at various times. If blood glucose levels can fail to predict onset of hypoglycaemic episodes, healthcare professionals may need to broaden the range of blood glucose readings that might indicate a hypoglycaemic episode and tailor specific advice to individual patients. To reduce the use of emergency services, more attention must be paid to hypoglycaemia unawareness and better advice provided about this condition. Also, more education should be provided for family members/carers, given the crucial role they play in the management of diabetes and hypoglycaemic episodes, and being a link in the process leading to increased use of emergency services. The HEBC could be developed into a useful ‘screening tool’ to help healthcare professionals identify those at greater risk of hypoglycaemic episodes and those at greater risk of long-term complications, and to target advice more specifically to these patient groups. Further research could explore family member/carer knowledge in more detail to better understand their role in helping to manage hypoglycaemic episodes.

Animal and human studies have consistently demonstrated that recurrent hypoglycaemia (RH) blunts both hormonal and behavioral counter regulatory responses (CRR) to further episodes of hypoglycaemia. It is now well established that the brain is involved in regulating whole-body glucose homeostasis, including the CRR to hypoglycaemia. The aim of the current study was to investigate if adaptations occur, following RH, which are intrinsic to glucose-sensing neurons in the absence of synaptic/glial inputs or signals from the periphery. Utilising the GT1-7 hypothalamic mouse cell line as an in vitro model of homogenous glucose-excited neurons, the current study has demonstrated that recurrent low glucose exposure reprograms intracellular metabolism towards a “hypometabolic state”. This result occurs in conjunction with an attenuated ability of the cells to hyperpolarise in response to low glucose and a reduction in the sensitivity of the KATP channel to activation by MgADP. In an attempt to reverse the changes observed in KATP channel activity, the SUR1-selective KATP channel opener, NN414, was applied chronically to GT1-7 cells. However, chronic KATP channel activation severely reduced channel conductance and sensitivity to activation by MgADP and further NN414 application. These results suggest that chronic activation of the KATP channel leads to the induction of a negative feedback mechanism to reduce channel activity. This may be in an attempt to maintain neuronal membrane potential within a physiological range. These results also suggest activation of central KATP channels during RH may be driving the resulting defective CRR. However, adaptations in metabolism following RH may also be altering the function of central KATP channels.

The tumor microenvironment consists of multiple cells types, including endothelial cells that line the tumor vasculature. Tumor vasculature is often abnormal and results in development of tissue ischemia, another contributing factor to the tumor microenvironment. Previous studies have demonstrated that ischemia influences epigenetic programming, but the mechanisms remained unclear and required further investigation. First, we profiled DNA methyltransferase (DNMT) expression and activity in human colorectal cancer cells (HCT116) under hypoxia or hypoglycaemia (mimicking ischemia). We found that DNMT1 and DNMT3b were significantly downregulated by hypoxia and hypoglycaemia, and DNMT3a was downregulated by hypoglycaemia. However, DNMT1 downregulation was p53-dependent. To examine if the changes in DNMT expression and activity translated to changes in DNA methylation patterns, we used bisulfite sequencing and examined the promoter region of p16. Hypoglycaemia significantly demethylated this region in both p53 wild-type and p53-null cells. Next, we used a genome-wide approach to discover what additional genes are hypomethylated by ischemia. Methylated DNA was immunoprecipitated and analysed with an Affymetrix promoter array, in parallel with an expression array. Ingenuity pathway analysis software revealed that a significant proportion of genes which were hypomethylated and upregulated were involved in cellular movement, including PLAUR and CYR61. We believe that hypoxia and hypoglycaemia may be driving changes in DNA methylation through dysregulation of DNMTs, resulting in cells acquiring a more mobile phenotype in ischemic regions. DNMT and histone deacetylase inhibitors are commonly used in research and some cancer therapies. Modifying epigenetic patterning with these inhibitors has been widely studied in cancer cells, but only briefly explored in the tumor’s vascular endothelium. We profiled the effect of these inhibitors on endothelial cell (EC) behaviour, and tested if combining them with a targeted anti-angiogenic therapy would augment the inhibition of angiogenesis. When the DNMT inhibitor 5-aza-2’-deoxycytidine was combined with sunitinib, inhibition of EC proliferation was enhanced compared to treatment with sunitinib alone. EC migration was also inhibited by the combination of these two inhibitors, but not in an additive manner. These studies have improved our understanding of how altering epigenetic patterning with ischemia and therapeutic inhibitors can influence colorectal cancer and endothelial cell behaviour. / Canadian Cancer Society Research Institute. The Cancer Research Society.

Background: Insulin is an important hormone for glucose homeostasis. It is released from β-cells in the endocrine pancreas as a response to increased concentrations of plasma glucose. The major effect of insulin is the facilitation of cellular uptake and storage of glucose as glycogen. Insulinomas are tumours that produce excessive amounts of insulin resulting in hypoglycaemia. The condition has been observed in dogs and cats and is often malignant. One part of establishing the diagnosis is confirmation of elevated concentrations of insulin in a hypoglycaemic sample. Aim: The aim of this study was to evaluate if an equine-optimized insulin ELISA (Mercodia AB, Uppsala, Sweden) is useful for analysis of insulin in canine and feline serum samples when insulinoma is suspected. Material and methods: All samples were analysed with Equine insulin ELISA. Precision, linearity and effects of haemolysis were studied. The stability of insulin was evaluated after storage in 4°C, room temperature and after repeated freezing and thawing. A reference interval was constructed for both canine and feline samples. Results: Total precision expressed as CV was 4.4 – 18.9 %. The method was linear up to at least 100 mU/L for dogs and 15 mU/L for cats. Reference interval for cats was <11.6 mU/L, due to few healthy animals no reference interval for dogs could be established. Stability was acceptable for up to four days. No effects of haemolysis were detected. Conclusion: Mercodia Equine insulin ELISA is suitable for analysis of insulin in serum from dogs and cats when suspecting insulinoma.

Abstract Present Situation: Research investigation deals with nursing care of the child with glycogen storage disease type I., as well as its diagnosis, nutritional management and complications. Glycogen storage disease (GSD) belongs among rare hereditary metabolic disorders. There are several types of GSD, divided into hepatic, myopathic and generalized forms. Early diagnosis is essential for effective treatment of the disease, the signs and symptoms of which first appear in babies soon after birth. The aim of this thesis was to describe the nursing care of the child with glycogen storage disease type I and identify the problems parents of affected children have to face. Methodology: Quantitative research method was used for empirical part of the thesis. The data collection was carried out through In-depth interviews with paediatric-ward nurses and a mother of the child with GSD type I. All interviews were audio recorded, transcribed and coded using paper-and-pencil method and finally categorized. The research sample consisted of nine paediatric-ward nurses and the mother taking care of the child with glycogen storage disease type I, also known as Gierke's disease. Selection of the sample was purposive and its size was determined by theoretical saturation of data. Results: Nursing care of children with glycogenosis type I requires regular feedings of a special diet enriched with corn starch substances to maintain the level of glycemia in the physiological range and to avoid dangerous hypoglycaemia. Problems for nursing staff mainly involve the unstable health condition of a child, fluctuating glycemia levels and limited knowledge of the disease. Parents not only worry about potential health complications of their child but they are also concerned about technical problems with feeding aids, poor recognition of hypoglycaemia and the child's mental welfare. The disease presents increased physical and emotional demands on the patient and their family. Conclusions and recommendations for practice: The thesis presents an outlook on the issue of paediatric-ward nursing care of the child with glycogen storage disease type I and indicates the common problems of the family with a child affected by the disease. The effort was to thoroughly understand the nature of the disease and to identify basic nursing care procedures which can benefit nurses in other facilities dealing with the same diagnosis. The results of the research will be presented in the magazine "Pediatrie pro praxi" in the nursing section.

Abstract Hypoglycaemia may contribute to the nocturnal occurrence of sudden death in type 1 diabetes. The impact of hypoglycaemia on cardiac autonomic regulation and electrical properties is a potential factor predisposing patients to fatal arrhythmic events.This study was designed to assess the effects of hypoglycaemia on cardiovascular autonomic regulation and cardiac repolarisation in type 1 diabetic patients and their non-diabetic counterparts during experimental and spontaneous hypoglycaemia. Sixteen subjects with type 1 diabetes and eight healthy controls participated in experimental hypoglycaemia induced by using glucose clamp technique. Altogether 37 patients with type 1 diabetes were evaluated in real-life situation by using continuous glucose monitoring system. Ten of those individuals participated in additional experiment to determine the effect of sympathetic activation on the cardiac autonomic regulation. Continous electrogram recordings were used to analyze heart rate variability (HRV) and cardiac repolarisation. During experimental hypoglycaemia, cardiac vagal activity, assessed by the high frequency (HF) component and beat-to-beat R-R interval variability (SD1), decreased progressively with no differences among diabetic or non-diabetic subjects. Controlled hypoglycaemia evoked profound changes in cardiac repolarisation. These changes tended to be even more evident in the diabetic subjects compared to those encountered in their healthy counterparts. During spontaneous hypoglycaemia, the low frequency (LF) component of HRV decreased significantly and correlated positively with the change in the glucose concentration. The muscle sympathetic nerve activity study confirmed that the reduction in the LF spectral component resulted mainly from pure sympathetic activation without any concomitant vagal withdrawal. Spontaneous hypoglycaemia induced significant changes in T-wave loop morphology. The QT interval corrected for heart rate by Bazett´s formula and by the nomogram method shortened during hypoglycaemia. The present observations indicate that hypoglycaemia has major impacts on cardiac autonomic regulation and repolarisation which may partly explain the vulnerability of these individuals to life-threatening cardiac arrhythmias and may have some clinical importance in contributing to the occurrence of ´dead-in-bed` syndrome. / Tiivistelmä Hypoglykemia saattaa vaikuttaa yöllisten äkkikuolemien ilmaantuvuuteen tyypin 1 diabetesta sairastavilla. Hypoglykemian vaikutus sydämen autonomiseen toimintaan ja sähköisiin ominaisuuksiin voi altistaa potilaat kuolemaan johtaville rytmihäiriölle. Tämän tutkimuksen tarkoitus oli selvittää hypoglykemian vaikutuksia kardiovaskulaarisen autonomisen toiminnan säätelyyn ja sydämen repolarisaatioon tyypin 1 diabetesta sairastavilla ja heidän terveillä verrokeillaan kokeellisen ja spontaanin hypoglykemian aikana. Kuusitoista diabetesta sairastavaa ja 8 verrokkipotilasta osallistuivat kokeellisen hypoglykemian tutkimukseen. Yhteensä 37 tyypin 1 diabetesta sairastavaa seurattiin jatkuvan sokeriseurannan laitteella kotioloissa. Kymmenen heistä osallistui jatkotutkimukseen, jossa selvitettiin sympaattisen aktivaation vaikutusta sydämen autonomisen toiminnan säätelyyn. Jatkuvaa sydänfilmin rekisteröintiä käytettiin sydämen sykevaihtelun ja repolarisaation analysoinnissa. Kokeellisen hypoglykemian aikana sydämen vagaalinen aktiivisuus määriteltynä korkean taajuuden (HF) komponentin osuutena ja R-R-välin vaihteluna (SD1) väheni progressiivisesti sekä diabetesta sairastavilla että verrokeilla. Kontrolloitu hypoglykemia aiheutti huomattavia muutoksia sydämen repolarisaatioon. Nämä muutokset olivat jopa suurempia diabetesta sairastavilla kuin heidän terveillä verrokeillaan. Spontaanin hypoglykemian aikana sykevaihtelun matalan taajuuden (LF) komponentin osuus pieneni huomattavasti ja korreloi positiivisesti sokeripitoisuuden muutokseen. Lihaksen sympaattisen hermoston aktiivisuutta koskeva tutkimus vahvisti, että matalan taajuuden osuuden pieneneminen johtui pääasiassa sympaattisesta aktivaatiosta eikä niinkään vagaalisen osuuden pienenemisestä. Spontaani hypoglykemia aiheutti merkittäviä muutoksia T-aallon sähköisen silmukan morfologiaan. Bazett’n kaavalla ja nomogrammimenetelmällä korjattu QT-väli lyheni hypoglykemian aikana. Tehdyt havainnot osoittavat, että hypoglykemialla on sellaisia merkittäviä vaikutuksia sydämen autonomisen toiminnan säätelyyn ja repolarisaatioon, jotka voivat osittain selittää näiden yksilöiden alttiuden henkeä uhkaaville rytmihäiriöille. Näillä muutoksilla voi olla kliinistä merkitystä ns. ”dead in bed”-oireyhtymän esiintymisessä.

Diabetes prevalence is increasing in our ageing and increasingly obese society. Diabetes is a heterogeneous condition, and challenges remain in all aspects of its management - from diagnosis through to optimising treatment, to managing complications. Increasing age brings altered physiological responses to disease, treatments and complications - and there may be more wide-ranging considerations such as dietary, mobility, dependency or cognition, to name just a few. Hypoglycaemia is one of the most important potential side-effects of insulin-therapy, and elderly adults are at particular risk from its consequences. Insulin-treated patients may have long-standing Type 1 diabetes, or have Type 2 diabetes which has progressed to requiring insulin treatment, due to progressive beta cell deficiency. Even within this group of patients, there is heterogeneity, and assessment of risks can be challenging. Endogenous insulin levels can be assessed by measuring C-peptide. Recent advances in this has meant this is much more practical, enabling assessment of endogenous levels in large numbers of patients more feasible, and hence allowing important questions to be addressed. In the context of older patients, particularly interesting questions are whether patients with long-standing Type 2 diabetes can develop severe insulin deficiency, and whether absolute/severe endogenous insulin levels have an impact on treatment or complications of diabetes within insulin-treated cohorts – such as hypoglycaemia. This may thence raise the question of whether C-peptide measurement could potentially be used as an extra clinical tool for risk assessment in a patient population which can be tricky to manage at times. The aim of this thesis is thus to explore some of the issues around management of diabetes in the elderly: in particular hypoglycaemia, and use of C-peptide to more fully assess patients and consider a possible role for it in routine clinical care of some patients. Chapter 1 puts the thesis in context, firstly reviewing hypoglycaemia in the elderly in general, and then considering aspects of endogenous insulin levels and C-peptide measurement. Chapter 2 addresses the problem of recognition of hypoglycaemia in an elderly population, using primary care records and documented symptoms at consultations. Are we missing hypoglycaemia in this population? Accurate diagnosis of diabetes is crucial for getting people on the right treatment guidelines, and can be challenging. Chapter 3 uses a spot urine measure of C-peptide to test for the first time the accuracy of the UK Practical Classification Guidelines (published by the Royal College of General Practitioners and NHS Diabetes). Progressive insulin deficiency in Type 2 diabetes is the main reason people with long-standing Type 2 diabetes may eventually require insulin treatment. Chapter 4 uses the spot urine measure of C-peptide as a screening tool to assess if insulin-treated people with a clinical diagnosis of Type 2 diabetes may develop absolute insulin deficiency. Even more practical than a spot urine test to measure C-peptide, could be a random non-fasting blood measure of C-peptide, which could thus be measured when patients have their routine blood tests done in the community or outpatient appointments. Chapter 5 looks at how such a measure correlates with the gold-standard mixed meal tolerance test C-peptide measure. Severe insulin deficiency in Type 1 diabetes has been correlated with increased complications including hypoglycaemia, but the impact of endogenous insulin levels has not been assessed greatly in Type 2 diabetes. Chapter 6 reports a study looking into this possible relationship, using hypoglycaemia questionnaire responses from a large number of community-dwelling insulin-treated adults (of both diagnoses), in the context of their clinical diabetes diagnosis and their random non-fasted blood C-peptide levels. Chapter 7 assesses in more detail the rates of hypoglycaemia in a small group of insulin-treated patients with a clinical diagnosis of Type 2 diabetes, selected on the basis of their endogenous C-peptide levels. As well as subjective assessment of their hypoglycaemia experience using questionnaires, continuous glucose monitoring was used to objectively assess their rates of hypoglycaemia and glucose variability. Chapter 8 pulls all the above chapters together, summarising them in the context of other research, discussing their limitations and possible areas for future research, and their implications for now for clinical practice.