Hypoglycemia in chronic kidney disease Radhika C K Assistant professor Govt .nursing college Thiruvananthapuram. Abstract Hypoglycemia is a significant issue among chronic kidney disease population. Management requires early identification and judicious use of drugs. This review narrates various aspects of uremic hypoglycemia by focusing on individually tailored therapy. Keywords: hypoglycemia; chronic kidney disease; diabetes; diabetic nephropathy; uremic hypoglycemia Introduction Prevalence of chronic kidney disease among diabetic population is alarmingly high [1, 2]. Chronic kidney disease (CKD) is a major micro vascular complication of diabetes and the inherent risk of hypoglycemia among diabetes get amplified in CKD [3]. Though achieving an optimum glycemic status is the prime concern of health professionals, it’s still a mirage due to the peculiar micro environment of a diabetic - CKD duo. Managing this clinical chaos is often a “balancing game” for many clinicians. This review article discusses the various aspects of uremic hypoglycemia. Epidemiology Despite the escalating rates of diabetic kidney disease, a precise statistics of hypoglycemia among diabetic CKD especially in India is lacking. Because mild fluctuations may not be clinically evident and also hypoglycemic unawareness - reduced ability or failure to recognize hypoglycemia at the physiological plasma glucose concentration at which warning symptoms normally occur- impairs prompt identification of a hypoglycemic episode [4, 5]. Moreover a complete analysis of glycemic status cannot be made by the conventional blood 1 glucose measures. Only continuous glucose monitoring facilitates absolute detection of hypoglycemia over stipulated periods [6]. A retrospective cohort study by Moen et al has reported greater risk of cardiovascular mortality among CKD patients from recurrent hypoglycemia and hypoglycemic unawareness. They found that the adjusted rate of hypoglycemia was higher in patients with CKD than those without CKD. Similarly regardless of severity, the rate of hypoglycemia among patients with diabetes was higher than in patients without diabetes. And finally higher rates of hypoglycemia were observed among patients who had both diabetes and CKD than either disease state alone. So it is evident that both diabetes and CKD are independent risk factors for hypoglycemia [7]. Findings from the famous ACCORD study also revealed that detected and undetected hypoglycemia was more common in the intensively treated group than in the standard group. A statistically significant relationship also established between the number of hypoglycemic episodes and the risk of death among participants [8]. The major UK Hypoglycemia Study Group reported that incidence of severe hypoglycemia is more among type 1 diabetes than type 2 [9]. Findings from the systematic review by the department of veteran’s affairs, Washington DC revealed that the incidence of severe hypoglycemia ranges between 0 - 3% per year for adults with type 2 diabetes on anti-diabetic drugs. The rate is highest in trials of people on insulin, sulfonylureas and regimens targeting intensive control of hemoglobin A1C (HbA1c) levels. For patients those who are on metformin, GLP-1 analogs, DPP-4 inhibitors, glinides and TZDs, the risk is negligible [10]. Often CKD is associated with a multitude of metabolic risk factors like hyperlipidemia, hypertension and diabetes. So the exact role of hypoglycemia in CKD mortality cannot be ascertained [4]. But many experimental studies have shown that clinical hypoglycemia can cause abnormal cardiac repolarization and an attendant risk of cardiac arrhythmia [11-13]. A prospective, randomized study from Asia investigated the relationships of hypoglycemia with total mortality and cardiovascular events and found that symptomatic hypoglycemia, whether clinically mild or severe, is associated with an increased risk of cardiovascular events, all-cause hospitalization, and all-cause mortality [14]. Hypoglycemia 2 Hypoglycemia is a clinical scenario where the plasma glucose levels will be abnormally low [15]. Because of wide individual variations a fixed cut off value is lacking. A diagnosis of hypoglycemia can be made with the help of a framework – Whipple’s triad. (1) Symptoms consistent with hypoglycemia, (2) a low plasma glucose concentrations, (3) relief of symptoms after the plasma glucose level is raised [15]. The American Diabetes Association and Endocrine Society workgroup on hypoglycemia (2012) has put forwarded a clear definition on iatrogenic hypoglycemia. i.e. all episodes of an abnormally low plasma glucose concentration that expose the patient to potential harm. The group suggested the following classification system for hypoglycemia [16]. Table 1. Classification of hypoglycemia [5] [The American Diabetes Association and Endocrine Society workgroup on hypoglycemia (2012)] Category Severe hypoglycemia Description An event requiring assistance of another person to actively administer carbohydrates. Documented An event during which typical symptoms of hypoglycemia are symptomatic accompanied by a measured plasma glucose concentration ≤70 mg/dL hypoglycemia (≤3.9 mmol/L). Asymptomatic An event not accompanied by typical symptoms of hypoglycemia but hypoglycemia with a measured plasma glucose concentration ≤70 mg/dL Probable symptomatic hypoglycemia. Pseudohypoglycemia. An event during which symptoms typical of hypoglycemia are not accompanied by a plasma glucose determination but that was presumably caused by a plasma glucose concentration ≤70 mg/dL (≤3.9 mmol/L) An event during which the person with diabetes reports any of the typical symptoms of hypoglycemia with a measured plasma glucose concentration >70 mg/dL (>3.9 mmol/L) but approaching that level. Counter regulatory scenario in Hypoglycemia 3 Irrespective of the substantial variations in food intake and activity, plasma glucose levels are maintaining a relatively narrow therapeutic range ie, 60-150 mg/dL. Rigorous endocrinal feedback axis or counter regulatory mechanisms are the key players in this. This counter regulatory mechanism primarily constitutes break down of glycogen stores and gluconeogenesis. Response of catecholamines also critical as it stimulates glycogenolysis and gluconeogenesis and limits the tissue glucose utilization. In the event of a sustained hypoglycemic attack, growth hormones and cortisol also limits glucose utilization and enhances its production. The glucose threshold for these counter regulatory responses is dynamic and depends on various metabolic factors [15]. Etiology Major causes of Hypoglycemia includes intake of drugs - especially insulin and sulfonylureas, sepsis, hyperinsulinism, congenital metabolic disorders, ethanol, starvation and factitious factors [15]. Of the anti-diabetic drugs, sulfonylureas are the agents which most likely to increase the risk of hypoglycemia. A major systematic review by Health Services Research wing, USA found out that the incidence of severe hypoglycemia in patients treated with sulfonylureas was 1.2% (95% CI 0.9 to 1.5%) over a an average follow-up period of 2.4 years. Specific factors that might increase the risk of hypoglycemia include use of insulin secretagogues, missed meals, advanced age, duration of diabetes, and unawareness of hypoglycemia [10]. Clinical manifestations Generally hypoglycemic features fall into two domains i.e., neuroglycopenic and autonomic. Brain is highly sensitive to glucose deprivations so the neuroglycopenic symptoms of hypoglycemia range from behavioral changes, confusion, fatigue, seizure, loss of consciousness and finally death in prolonged severe hypoglycemic situations (glucose levels of less than 40 mg/dL). Palpitation, tremor, anxiety, sweating, parasthesia and hunger are the common adrenergic symptoms [15, 16]. The hypoglycemic manifestations often can be quite uncomfortable and perplexing. Patient may experience a variety of subjective feelings like aura, flashes, headache and generalized weakness. These complex experiences may lead to anticipatory fear, a phenomenon known as fear of hypoglycemia (FOH) [17]. 4 Significance of Hypoglycemia in CKD. Glycemic management in CKD is complex because of a variety of factors like impaired peripheral insulin degradation, reduced insulin requirements, impaired glucose counter regulatory mechanisms and malnutrition. As renal function deteriorates over time, prolonged half-life of antidiabetic drugs also aggravates the glycemic status. Constellation of these all factors may exaggerate the implied risk of hypoglycemia in diabetic CKD patients [7, 18]. Chronic kidney disease According to ‘National Kidney Foundation - Kidney Disease Outcome Quality Initiative’ (NKF KDOQI), Chronic Kidney Disease can be defined as kidney damage for three or more months, as defined by structural or functional abnormalities of the kidney, with or without decreased glomerular filtration rate (GFR), manifested by pathologic abnormalities or markers of kidney damage, including abnormalities in the composition of the blood or urine or abnormalities in imaging tests (GFR<60mL/minute/1.73 m2 for three months or more, with or without kidney damage) [19]. Classification of CKD is based on the Estimation of glomerular filtration rate (GFR). Estimation equations are derived based on the ser. creatinine value. Though validation in Indian setting is lacking, Modification of Diet in Renal Disease (MDRD) equation and the more recent CKD – EPI (Chronic Kidney Disease Epidemiology Collaboration) formula are commonly used [19, 20]. Table 2. Classification of CKD based on GFR (KDIGO 2012 guidelines) [21] CATEGORY DESCRIPTION GFR G1 Normal or high ≥90 G2 Mildly decreased 60–89 G3a Mildly to moderately decreased 45–59 G3b Moderately to severely decreased 30–44 G4 Severely decreased 15–29 G5 Kidney failure <15 5 Diabetic management strategies in CKD Glycemic management in CKD is a complex issue. Many factors like presence of comorbidities, poly pharmacy, fear of hypoglycemia and deterioration in quality of life, personal, economic and social factors may make the situation more intricate [4]. Optimization of glycemic control: Optimum glycemic control is the prime consideration among the therapeutic management of diabetic CKD. Goals need to be readjusted as per the renal status [24]. The worsening of kidney function in diabetes can be slowed through intensive glycemic control [25]. Judicious drug use: Many clinical trials are underway in this regard. Of the available anti diabetic agents, an intelligent selection and good prescribing practice should be followed [4, 19, 21, 23]. Till now, any particular agent cannot be preferred over another for renoprotective effect [25]. Apart from standardized treatment, individually tailored treatment is the current strategy [24, 29]. Glucose monitoring: Continuous glucose monitoring (CGM) lowers A1C by ~0.26% compared with SMBG. CGM may be a supplemental tool to SMBG in those with hypoglycemia unawareness and/or frequent hypoglycemic episodes [25]. Diffuse glycemic fluctuations in CKD can only be elicited through a CGM [26, 27, 28]. Patient education: Self-management education is vital in patients with diabetic kidney disease. And it should address psychosocial issues, since emotional well-being is associated with positive outcomes [24, 29]. Reevaluation: As hypoglycemia unawareness is a common phenomenon in CKD, one or more episodes of severe hypoglycemia should trigger re-evaluation of the treatment regimen. Glycemic targets should be reevaluated to strictly avoid further hypoglycemia for at least several weeks, to partially reverse hypoglycemia unawareness and reduce risk of future episodes [14, 23, 24]. Conclusions Hypoglycemia is a common clinical entity among diabetic patients and the risk is highest in patients with CKD and diabetes. It is an unintended consequence of therapy to treat. As it is an 6 iatrogenic independent risk factor for mortality, individually tailored pharmacologic therapy is vital. References 1. Plantinga LC, Crews DC, Coresh J, Miller ER , Saran R, Yee J, et al. Prevalence of chronic kidney disease in US adults with undiagnosed diabetes or pre diabetes. Clinical Journal of American Society of Nephrology. 2010; Apr; 5 (4):673-82. doi: 10.2215/CJN.07891109. Epub 2010 Mar 25. 2. Anupama Y. 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