Hypoglycaemia and counterregulation in type 2 diabetes

Association of hypoglycaemia with the risks of arrhythmia and mortality in individuals with diabetes - a systematic review and meta-analysis

Background

Hypoglycaemia has been linked to an increased risk of cardiac arrhythmias by causing autonomic and metabolic alterations, which may be associated with detrimental outcomes in individuals with diabetes(IWD), such as cardiovascular diseases (CVDs) and mortality, especially in multimorbid or frail people. However, such relationships in this population have not been thoroughly investigated. For this reason, we conducted a systematic review and meta-analysis.

Methods

Relevant papers published on PubMed, Embase, Cochrane, Web of Knowledge, Scopus, and CINHAL complete from inception to December 22, 2022 were routinely searched without regard for language. All of the selected articles included odds ratio, hazard ratio, or relative risk statistics, as well as data for estimating the connection of hypoglycaemia with cardiac arrhythmia, CVD-induced death, or total death in IWD. Regardless of the heterogeneity assessed by the I2 statistic, pooled relative risks (RRs) and 95% confidence intervals (CI) were obtained using random-effects models.

Results

After deleting duplicates and closely evaluating all screened citations, we chose 60 studies with totally 5,960,224 participants for this analysis. Fourteen studies were included in the arrhythmia risk analysis, and 50 in the analysis of all-cause mortality. Hypoglycaemic patients had significantly higher risks of arrhythmia occurrence (RR 1.42, 95%CI 1.21-1.68), CVD-induced death (RR 1.59, 95% CI 1.24-2.04), and all-cause mortality (RR 1.68, 95% CI 1.49-1.90) compared to euglycaemic patients with significant heterogeneity.

Conclusion

Hypoglycaemic individuals are more susceptible to develop cardiac arrhythmias and die, but evidence of potential causal linkages beyond statistical associations must await proof by additional specifically well planned research that controls for all potential remaining confounding factors.

Dietary Carbohydrate as Glycemic Load, Not Fat, Coupled with Genetic Permissiveness Favoring Rapid Growth and Extra Calories, Dictate Metabolic Syndrome and Diabetes Induction in Nile Rats (Arvicanthis niloticus)

Objective: Whether dietary carbohydrate (CHO) or fat is more involved in type 2 diabetes (T2DM) induction uncomplicated by dietary fiber was addressed in a spontaneous diabetic model, the diurnal Nile rat that mimics the human condition. Methods: A total of 138 male Nile rats were fed plant-based and animal-based saturated fat where 10% energy as CHO and fat were exchanged across 5 diets keeping protein constant, from 70:10:20 to 20:60:20 as CHO:fat:protein %energy. Diabetes induction was analyzed by: 1. diet composition, i.e., CHO:fat ratio, to study the impact of diet; 2. quintiles of average caloric intake per day to study the impact of calories; 3. quintiles of diabetes severity to study the epigenetic impact on diabetes resistance. Results: High glycemic load (GLoad) was most problematic if coupled with high caloric consumption. Diabetes severity highlighted rapid growth and caloric intake as likely epigenetic factors distorting glucose metabolism. The largest weanling rats ate more, grew faster, and developed more diabetes when the dietary GLoad exceeded their gene-based metabolic capacity for glucose disposal. Diabetes risk increased for susceptible rats when energy intake exceeded 26 kcal/day and the GLoad was >175/2000 kcal of diet and when the diet provided >57% energy as CHO. Most resistant rats ate <25 kcal/day independent of the CHO:fat diet ratio or the GLoad adjusted to body size. Conclusion: Beyond the CHO:fat ratio and GLoad, neither the type of fat nor the dietary polyunsaturated/saturated fatty acid (P/S) ratio had a significant impact, suggesting genetic permissiveness affecting caloric and glucose intake and glucose disposition were key to modulating Nile rat diabetes. Fat became protective by limiting GLoad when it contributed >40% energy and displaced CHO to <50% energy, thereby decreasing the number of diabetic rats and diabetes severity.

Hypoglycemia and glycemic variability are associated with mortality in non-intensive care unit hospitalized infectious disease patients with diabetes mellitus

AIMS/INTRODUCTION

We aimed to identify factors - glycemic control, reactive inflammatory biomarkers or vital signs - associated with mortality in diabetic patients admitted to hospital for various infections (non-intensive care unit).

MATERIALS AND METHODS

We retrospectively analyzed the cases of 620 diabetic patients admitted to hospital for various infections (non-intensive care unit) who underwent glucose monitoring >3 times per day. We extracted data regarding reactive inflammatory biomarkers and vital signs recorded on day 1 of hospital stay, and data on bacteremia and hypoglycemia status, glycemic variability (GV; coefficient of variation and standard deviation) and mean glucose concentrations during the entire hospital stay. Univariate and stepwise multivariate logistic regression analyses were carried out to determine the association between these factors and mortality.

RESULTS

The mortality rate was 10.1%. Reactive inflammatory biomarkers, vital signs and bacteremia were not associated with mortality. According to the results of the adjusted analysis, hypoglycemia showed a significant positive association with mortality, increasing death risk by 266% (odds ratio [OR] 2.66, 95% confidence interval [95% CI] 1.22-5.83; P = 0.0006). High coefficient of variation and standard deviation values were significantly associated with increased mortality, increasing death risk by 18% (OR 1.18, 95% CI 1.01-1.38; P = 0.03) and 9% (OR 1.09, 95% CI 1.01-1.18; P = 0.03), respectively. Mean glucose concentrations were also significantly associated with mortality, increasing death risk by 5% (OR 1.05, 95% CI 1.02-1.08; P = 0.0008).

CONCLUSIONS

Glycemic indices (especially hypoglycemia and GV), rather than reactive inflammatory biomarkers or vital signs, were associated with mortality in non-intensive care unit diabetes mellitus patients with infections.

Hypoglycemia in Patients with Diabetes and Renal Disease

This article summarizes our current knowledge of the epidemiology, pathogenesis, and morbidity of hypoglycemia in patients with diabetic kidney disease and reviews therapeutic limitations in this situation.

Hypoglycemia, chronic kidney disease, and diabetes mellitus

Hypoglycemia is a major problem associated with substantial morbidity and mortality in patients with diabetes and is often a major barrier to achieving optimal glycemic control. Chronic kidney disease not only is an independent risk factor for hypoglycemia but also augments the risk of hypoglycemia that is already present in people with diabetes. This article summarizes our current knowledge of the epidemiology, pathogenesis, and morbidity of hypoglycemia in patients with diabetes and chronic kidney disease and reviews therapeutic considerations in this situation. PubMed and MEDLINE were searched for literature published in English from January 1989 to May 2014 for diabetes mellitus, hypoglycemia, chronic kidney disease, and chronic renal insufficiency.

Hypoglycemia

Hypoglycemia remains a common problem for patients with diabetes and is associated with substantial morbidity and mortality. This article summarizes our current knowledge of the epidemiology, pathogenesis, risk factors, and complications of hypoglycemia in patients with diabetes and discusses prevention and treatment strategies.

Risk of hypoglycaemia in types 1 and 2 diabetes: effects of treatment modalities and their duration

AIMS/HYPOTHESIS

We explored the epidemiology of hypoglycaemia in individuals with insulin-treated diabetes by testing the hypothesis that diabetes type and duration of insulin treatment influence the risk of hypoglycaemia.

MATERIALS AND METHODS

This was an observational study over 9-12 months in six UK secondary care diabetes centres. Altogether 383 patients were involved. Patients were divided into the following three treatment groups for type 2 diabetes: (1) sulfonylureas, (2) insulin for <2 years and (3) insulin for >5 years, and into two treatment groups for type 1 diabetes, namely <5 years disease duration and >15 years disease duration. Self-reported (mild and severe) and biochemical episodes (interstitial glucose <2.2 mmol/l using continuous glucose monitoring) were recorded.

RESULTS

Mild hypoglycaemia in type 2 diabetic patients on insulin for <2 years was less frequent than in type 1 patients with <5 years disease duration (mean rate: 4 vs 36 episodes per subject-year, p < 0.001). In type 2 diabetic patients treated with sulfonylureas or insulin for <2 years, no differences were observed in the proportion experiencing severe hypoglycaemia (7 vs 7%, difference 0 [95% CI: -7 to 9%]), mild symptomatic (39 vs 51%, difference 12 [-3 to 25%]) or interstitial glucose <2.2 mol/l (22 vs 20%, difference 2 [-13 to 10%]). Severe hypoglycaemia rates were comparable in patients with type 2 diabetes on sulfonylureas or insulin < 2 years (0.1 and 0.2 episodes per subject-year) and far less frequent than in type 1 diabetes (<5 years group, 1.1; >15 years group, 3.2.episodes per subject-year).

CONCLUSIONS/INTERPRETATION

During early insulin use in type 2 diabetes, the frequency of hypoglycaemia is generally equivalent to that observed in patients treated with sulfonylureas and considerably lower than during the first 5 years of treatment in type 1 diabetes.

The importance of tight glycemic control

Macrovascular complications of diabetes are the leading cause of morbidity and mortality in patients with diabetes and may begin well before diabetes is diagnosed. The precise mechanism of how postprandial hyperglycemia contributes to the pathogenesis of cardiovascular disease is not fully known but may be a result of direct effects on the vasculature. Several epidemiologic studies have suggested that increased glycemic exposure, especially postchallenge or postprandial hyperglycemia, is an independent risk factor for macrovascular disease with no apparent upper or lower threshold. Evidence is emerging that this association is also present in the prediabetic and nondiabetic states. In fact, therapies targeting postprandial hyperglycemia have shown reductions in cardiovascular events in patients with impaired glucose tolerance. Meal-related self-monitoring of blood glucose can inform patients and their healthcare providers about postprandial glycemic excursions so that diet, exercise, or medications can be adjusted.

Reduced hypoglycemia risk with insulin glargine: a meta-analysis comparing insulin glargine with human NPH insulin in type 2 diabetes

OBJECTIVE

Insulin glargine (LANTUS) is a once-daily basal insulin analog with a smooth 24-h time-action profile that provides effective glycemic control with reduced hypoglycemia risk (particularly nocturnal) compared with NPH insulin in patients with type 2 diabetes. A recent "treat-to-target" study has shown that more patients on insulin glargine reached HbA(1c) levels < or =7.0% without confirmed nocturnal hypoglycemia compared with NPH insulin. We further assessed the risk for hypoglycemia in a meta-analysis of controlled trials of a similar design for insulin glargine versus once- or twice-daily NPH insulin in adults with type 2 diabetes.

RESEARCH DESIGN AND METHODS

All studies were 24-28 weeks long, except one 52-week study, for which interim 20-week data were used.

RESULTS

Patient demographics were similar between the insulin glargine (n = 1,142) and NPH insulin (n = 1,162) groups. The proportion of patients achieving target HbA(1c) (< or =7.0%) was similar between insulin glargine-and NPH insulin-treated patients (30.8 and 32.1%, respectively). There was a consistent significant reduction of hypoglycemia risk associated with insulin glargine, compared with NPH insulin, in terms of overall symptomatic (11%; P = 0.0006) and nocturnal (26%; P < 0.0001) hypoglycemia. Most notably, the risk of severe hypoglycemia and severe nocturnal hypoglycemia were reduced with insulin glargine by 46% (P = 0.0442) and 59% (P = 0.0231), respectively.

CONCLUSIONS

These results confirmed that insulin glargine given once daily reduces the risk of hypoglycemia compared with NPH insulin, which can facilitate more aggressive insulin treatment to a HbA(1c) target of < or =7.0% in patients with type 2 diabetes.

Insulin therapy and hypoglycaemia: the size of the problem

BACKGROUND AND METHODS

Hypoglycaemia is a fact of life for people with diabetes mellitus. Mild, asymptomatic episodes occur once or twice a week in insulin-treated diabetic subjects. Asymptomatic hypoglycaemia, including nocturnal hypoglycaemia, occurs in about 25% of diabetic subjects treated with insulin therapy. Mild hypoglycaemia, if recurrent, induces unawareness of hypoglycaemia and impairs glucose counterregulation, which in turn predisposes to severe hypoglycaemia. Even brief hypoglycaemia can cause profound dysfunction of the brain. Prolonged, severe hypoglycaemia can cause permanent neurological sequels. In addition, it is possible that hypoglycaemia may accelerate the vascular complications of diabetes by increasing platelet aggregation and/or fibrinogen formation. Finally, hypoglycaemia may be fatal. Hypoglycaemia induced by insulin as treatment of type 1 diabetes mellitus (T1 DM) is not the consequence of diabetes, but invariably of the non-physiological replacement of insulin.

RESULTS

A number of studies have demonstrated that by moving from non-physiological to more physiological models of insulin therapy, most of the hypoglycaemia problems may be overcome, the percentage of glycated hemoglobin (A1c) decreased, and the quality of life improved. Interestingly, in T1 DM with hypoglycaemia unawareness, prevention of hypoglycaemia reverses not only unawareness but also improves glucose counterregulation, primarily the responses of adrenaline.

CONCLUSIONS

In order to best prevent hypoglycaemia, insulin should preferably be given as continuous subcutaneous infusion via a minipump (the 'golden standard') or multiple daily insulin administrations with insulin analogues (basal insulin glargine, meal insulin rapid-acting insulin analogues) in T1 DM.

Renal compensation for impaired hepatic glucose release during hypoglycemia in type 2 diabetes: further evidence for hepatorenal reciprocity

During liver transplantation and after both meal ingestion and prolonged fasting, renal glucose release (RGR) increases while hepatic glucose release (HGR) decreases. These and other observations have led to the concept of hepatorenal reciprocity. According to this concept, reciprocal changes in hepatic and renal glucose release may occur to minimize deviations from normal glucose homeostasis. We further assessed this concept by testing the hypothesis that during counterregulation of hypoglycemia in patients with type 2 diabetes, who would be expected to have reduced HGR, RGR would be increased. Accordingly, we performed hypoglycemic hyperinsulinemic clamp experiments (approximately 3.1 mmol/l) in 12 type 2 diabetic and in 10 age-weight-matched nondiabetic volunteers and measured total endogenous glucose release (TEGR) and RGR using a combined isotopic net balance approach. HGR was calculated as the difference between TEGR and RGR since only these organs are capable of releasing glucose. We found that during comparable hypoglycemia and hyperinsulinemia, TEGR was reduced in type 2 diabetes (6.6 +/- 0.6 vs. 10.2 +/- 1.1 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.01) due to reduced HGR (3.9 +/- 0.5 vs. 8.6 +/- 1.0 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.0015). In contrast, RGR was increased approximately twofold in type 2 diabetes (3.3 +/- 0.5 vs. 1.6 +/- 0.3 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.015). Plasma epinephrine, lactate, and free fatty acid concentrations, which would promote RGR, were also greater in type 2 diabetes (all P < 0.01). Our results provide further support for hepatorenal reciprocity and may explain at least in part the relatively low occurrence of severe hypoglycemia in type 2 diabetes compared with type 1 diabetes where both HGR and RGR counterregulatory responses are reduced.