Management of diabetes in people with advanced chronic kidney disease.

Diabetes is the commonest cause of end stage kidney disease globally, accounting for almost 40% of new cases requiring renal replacement therapy. Management of diabetes in people with advanced kidney disease on renal replacement therapy is challenging due to some unique aspects of assessment and treatment in this group of patients. Standard glycaemic assessment using glycated haemoglobin may not be valid in such patients due to altered red blood cell turnover or iron/erythropoietin deficiency, leading to changed red blood cell longevity. Therefore, use of continuous glucose monitoring may be beneficial to enable more focussed glycaemic assessment and improved adjustment of therapy. People with advanced kidney disease may be at higher risk of hypoglycaemia due to a number of physiological mechanisms, and in addition, therapeutic options are limited in such patients due to lack of experience or license. Insulin therapy is the basis of treatment of people with diabetes with advanced kidney disease due to many other drugs classes being contraindicated. Targets for glycaemic control should be adjusted according to co-morbidity and frailty, and continuous glucose monitoring should be used in people on dialysis to ensure low risk of hypoglycaemia. Post-transplant diabetes is common amongst people undergoing solid organ transplantation and confers a greater risk of mortality and morbidity in kidney transplant recipients. It should be actively screened for and managed in the post-transplant setting.

Could metformin be used in patients with diabetes and advanced chronic kidney disease?

Diabetes is an important cause of end stage renal failure worldwide. As renal impairment progresses, managing hyperglycaemia can prove increasingly challenging, as many medications are contra-indicated in moderate to severe renal impairment. Whilst evidence for tight glycaemic control reducing progression to renal failure in patients with established renal disease is limited, poor glycaemic control is not desirable, and is likely to lead to progressive complications. Metformin is a first-line therapy in patients with Type 2 diabetes, as it appears to be effective in reducing diabetes related end points and mortality in overweight patients. Cessation of metformin in patients with progressive renal disease may not only lead to deterioration in glucose control, but also to loss of protection from cardiovascular disease in a cohort of patients at particularly high risk. We advocate the need for further study to determine the role of metformin in patients with severe renal disease (chronic kidney disease stage 4-5), as well as patients on dialysis, or pre-/peri-renal transplantation. We explore possible roles of metformin in these circumstances, and suggest potential key areas for further study.

Managing diabetes in dialysis patients.

Burgeoning levels of diabetes are a major concern for dialysis services, as diabetes is now the most common cause of end-stage renal disease in most developed nations. With the rapid rise in diabetes prevalence in developing countries, the burden of end stage renal failure due to diabetes is also expected to rise in such countries. Diabetic patients on dialysis have a high burden of morbidity and mortality, particularly from cardiovascular disease, and a higher societal and economic cost compared to non-diabetic subjects on dialysis. Tight glycaemic and blood pressure control in diabetic patients has an important impact in reducing risk of progression to end stage renal disease. The evidence for improving glycaemic control in patients on dialysis having an impact on mortality or morbidity is sparse. Indeed, many factors make improving glycaemic control in patients on dialysis very challenging, including therapeutic difficulties with hypoglycaemic agents, monitoring difficulties, dialysis strategies that exacerbate hyperglycaemia or hypoglycaemia, and possibly a degree of therapeutic nihilism or inertia on the part of clinical diabetologists and nephrologists. Standard drug therapy for hyperglycaemia (eg, metformin) is clearly not possible in patients on dialysis. Thus, sulphonylureas and insulin have been the mainstay of treatment. Newer therapies for hyperglycaemia, such as gliptins and glucagon-like peptide-1 analogues have become available, but until recently, renal failure has precluded their use. Newer gliptins, however, are now licensed for use in 'severe renal failure', although they have yet to be trialled in dialysis patients. Diabetic patients on dialysis have special needs, as they have a much greater burden of complications (cardiac, retinal and foot). They may be best managed in a multidisciplinary diabetic-renal clinic setting, using the skills of diabetologists, nephrologists, clinical nurse specialists in nephrology and diabetes, along with dietitians and podiatrists.

Prevalence of cognitive impairment in patients attending pre-dialysis clinic.

Approximately 20-30% of patients on renal replacement therapy (RRT) have cognitive impairment. Less is known about the prevalence of cognitive impairment in patients with advanced kidney disease awaiting the initiation of dialysis. Routine cognitive assessment was implemented in the pre-dialysis clinic, which enabled the Nephrologist and Pre-dialysis Nurse to identify those patients with impaired cognitive function and utilise this information to assess the suitability for self-care treatments, such as peritoneal dialysis, as well as to adapt information to meet their needs. Subsequently, a cross-sectional single-centre audit was undertaken to identify the prevalence of cognitive impairment in 132 consecutive new referrals to the pre-dialysis clinic using the Mini-mental State Examination (MMSE). Twenty percent (95% CI = 0.13, 0.27) were classified as cognitively impaired. Those with cognitive impairment were significantly older, and had lower eGFR and higher serum creatinine. It can be concluded that approximately 1 in 5 patients attending the pre-dialysis clinic has cognitive impairment, which may not be apparent on a routine clinical history. Cognitive function assessment is recommended for all, but particularly to the older patient, before advising on choice of dialysis modality or opting for conservative treatment.