A pilot longitudinal study of the use of waxy maize heat modified starch in the treatment of adults with glycogen storage disease type I: a randomized double-blind cross-over study

Short and long-term acceptability and efficacy of extended-release cornstarch in the hepatic glycogen storage diseases: results from the Glyde study

BACKGROUND

Hypoglycaemia is the primary manifestation of all the hepatic types of glycogen storage disease (GSD). In 2008, Glycosade®, an extended-release waxy maize cornstarch, was reported as an alternative to uncooked cornstarch (UCCS) which could prolong the duration of fasting in the GSD population. To date, there has been minimal published experience in (a) young children, (b) the ketotic forms of GSD, and (c) with daytime dosing. The Glyde study was created as a prospective, global initiative to test the efficacy and tolerance of Glycosade use across a broader and more diverse population.

METHODS

A randomised double-blind cross-over fasting study assessing the tolerance and efficacy of Glycosade compared with cornstarch was performed across disease types and ages. Participants and clinicians chose the product deemed superior, whilst still blinded. Participants were followed for 2 years to assess long-term metabolic control, growth, and quality of life.

RESULTS

Sixty-one participants (age 2-62 years; 59% female) were enrolled, and 58 participants completed the fasting studies (28 GSD I; 30 GSD III, VI, IX). Glycosade improved duration of fasting in GSD I and duration of fasting without ketosis in the ketotic forms. Chronic Glycosade use was chosen by 69% of participants. Those treated with Glycosade for the 2-year chronic phase used fewer doses of therapy while markers of metabolic control remained stable.

CONCLUSION

The Glyde study is the first multi-centre international trial demonstrating the efficacy and tolerance of Glycosade in a large cohort of hepatic GSD patients across a diverse international population. The ability to use fewer doses of therapy per day and avoidance of overnight therapy may improve compliance, safety, and quality of life without sacrificing metabolic control.

Savory Cracker Development for Blood Glucose Control and Management: Glycogen Storage Diseases

The blood glucose response of savory slow energy-release crackers (GLY-HYP) were evaluated in volunteers carrying glycogen storage diseases (GSDs), Types I (Ia) and IV. The crackers have been shown previously to provide a "flat" slow glucose response in healthy volunteers, for up to 4 h. On average for the mixed-sex volunteer group aged 53 to 70 for Type I, the blood glucose concentration increased from baseline to a maximum of 9.5 mmol/L at 60 min and remained above baseline for up to 210 min; overall, above 5 mmol/L for 4 h. In common with healthy individuals, a relatively flat blood glucose response was recorded. For Type IV, mixed-sex patients aged between 55 and 72, the blood glucose concentration reached maximum of 10.2 mmol/L at 45 min and then stayed above baseline for 150 min. Again, overall, above 5 mmol/L for 4 h. Altogether, these data indicate that these crackers would provide a valuable contribution to the nutritional needs of people of different age groups with GSDs (Clinical Registration Number: HRC10032021).

Bedtime extended release cornstarch improves biochemical profile and sleep quality for patients with glycogen storage disease type Ia

BACKGROUND

Patients with glycogen storage disease type Ia (GSDIa) are prone to hypoglycemia. Uncooked cornstarch (CS) is the treatment, but maintaining nighttime blood glucose levels is still difficult.

METHODS

The study enrolled patients with GSDIa to investigate the benefits of bedtime extended release CS (ER-CS, Glycosade®) versus regular CS. The daytime CS schedule was not altered. A 7-day continuous glucose monitoring (CGM) was performed at the baseline and 12 weeks after using ER-CS. Biochemical profile, sleep quality (Pittsburgh Sleep Quality Index, PSQI), and quality of life (SF-36 questionnaire) were measured at the baseline and 24 weeks after using ER-CS.

RESULTS

Nine patients (9 to 33 years of age) were enrolled. Compared with the baseline (80.0 ± 6.33 mg/dL), the 12-week evaluations revealed higher mean morning glucose levels (86.5 ± 8.26 mg/dL, p = 0.015). Twenty-four weeks after the use of bedtime ER-CS, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels both decreased (from 69.3 ± 77.8 to 41.1 ± 40.4 U/L and from 78.8 ± 99.6 to 37.8 ± 28.81 U/L, respectively, p = 0.013 for both analyses), and sleep and fasting time both elongated (from 7.8 ± 0.87 to 8.6 ± 1.02 h and from 6.5 ± 1.22 to 7.6 ± 1.02 h, respectively, p = 0.011 for both analyses). The mean PSQI score in the five adult patients decreased significantly (from 5.8 ± 1.29 to 3.0 ± 1.71, p = 0.042).

CONCLUSION

This study provides evidence of clinically meaningful improvements by shifting only bedtime regular CS to ER-CS in patients with GSDIa. As ER-CS is considerably more expensive than regular CS, this approach presents a cost-effective alternative.

French recommendations for the management of glycogen storage disease type III

The aim of the Protocole National De Diagnostic et de Soins/French National Protocol for Diagnosis and Healthcare (PNDS) is to provide advice for health professionals on the optimum care provision and pathway for patients with glycogen storage disease type III (GSD III).The protocol aims at providing tools that make the diagnosis, defining the severity and different damages of the disease by detailing tests and explorations required for monitoring and diagnosis, better understanding the different aspects of the treatment, defining the modalities and organisation of the monitoring. This is a practical tool, to which health care professionals can refer. PNDS cannot, however, predict all specific cases, comorbidities, therapeutic particularities or hospital care protocols, and does not seek to serve as a substitute for the individual responsibility of the physician in front of his/her patient.

A triple-blinded crossover study to evaluate the short-term safety of sweet manioc starch for the treatment of glycogen storage disease type Ia

Background

Glycogen storage disease type 1a (GSD Ia) is characterized by severe fasting hypoglycemia. The clinical management includes the administration of uncooked cornstarch (UCCS). Although such a diet approach is effective in achieving euglycemia, its impact on the quality of life of patients should be considered. In vitro analyses suggest a longer release of glucose when using sweet manioc starch (SMS).

Methods

We compared the efficacy and safety of the administration of SMS and UCCS during a short-fasting challenge in patients with GSD Ia in a randomized, triple-blind, phase I/II, cross-over study. GSD Ia patients aged ≥ 16 years and treated with UCCS were enrolled. Participants were hospitalized for two consecutive nights, receiving UCCS or SMS in each night. After the administration of the starches, glucose, lactate and insulin levels were measured in 1-h interval throughout the hospitalization period. The procedures were interrupted after 10 h of fasting or in a hypoglycemic episode (< 3.88 mmol/L).

Results

Eleven individuals (mean age: 21.6 ± 4.3 years; all presenting body mass index > 25 kg/m²) participated in the study. The average fasting period was 8.2 ± 2.0 h for SMS and 7.7 ± 2.3 h for UCCS (p = 0.04). SMS maintained euglycemia for a greater period over UCCS. Increased lactate concentrations were detected even in absence of hypoglycemia, not being influenced by the different starches investigated (p = 0.17). No significant difference was found in total cholesterol, HDL, triglycerides and uric acid levels in both arms. None of the patients showed severe adverse events.

Conclusions

SMS appears to be non-inferior to UCCS in the maintenance of euglycemia, thus emerging as a promising alternative to the treatment of GSD Ia.

Uncooked cornstarch for the prevention of hypoglycemic events

Hypoglycemia is a pathological condition characterized by a low plasma glucose concentration associated with typical autonomic and/or neuroglycopenic symptoms, and resolution of these symptoms with carbohydrate consumption. Hypoglycemia is quite common in clinical practice, particularly in insulin-treated patients with diabetes and in other inherited or acquired conditions involving the regulation of glucose metabolism. Beyond symptoms that might strongly affect the quality of life, hypoglycemia can lead to short- and long-term detrimental consequences for health. Hypoglycemia can be prevented by appropriate changes in dietary habits or by relevant modifications of the drug treatment. Several dietary approaches based on the intake of various carbohydrate foods have been tested for hypoglycemia prevention; among them uncooked cornstarch (UCS) has demonstrated a great efficacy. In this narrative review, we have summarized the current evidence on the UCS usefulness in some conditions characterized by high hypoglycemic risk, focusing on some inherited diseases -i.e. glycogen storage diseases and other rare disorders - and acquired conditions such as type 1 diabetes, postprandial hypoglycemia consequent to esophageal-gastric or bariatric surgery, and insulin autoimmune syndrome. We also considered the possible role of UCS during endurance exercise performance. Lastly, we have discussed the dose requirement, the side effects, the limitations of UCS use, and the plausible mechanisms by which UCS could prevent hypoglycemia.

Use of waxy maize heat modified starch in the treatment of children between 2 and 5 years with glycogen storage disease type I: A retrospective study

Background

Glycogen storage disease type I (GSDI) is caused by deficiency of the enzyme glucose-6-phosphatase or glucose-6-phosphate transporter. Mainstay of treatment is provision of uncooked cornstarch (and/or continuous nocturnal pump feed (CNPF) to maintain normoglycemia). Waxy maize heat modified starch (WMHMS) is another treatment option to maintain normoglycemia overnight. Our objective was to describe our experience treating children 2–5 years of age with GSDI using WMHMS overnight.

Method

This is a retrospective case series review (n = 5) comparing the overnight feeding regimen and biochemical control one year before and after nocturnal WMHMS therapy. The WMHMS trial, in which blood glucose and lactate levels were monitored hourly, is reported in detail.

Results

Most patients successfully transitioned to nocturnal WMHMS feeds. These patients had stable glucose and lactate throughout the overnight period, permitting a fasting period of 6.5–8 h overnight. Within the time period studied, WMHMS appeared to have improved overnight control of blood glucose levels with fewer reported episodes of hypoglycemia compared to CNPF.

Conclusion

WMHMS can be an effective substitute treatment to achieve stable nocturnal glucose control in children younger than five years of age. A larger multicenter prospective study is recommended to establish stronger evidence of the efficacy and safety of using WMHMS in treatment of young children with GSDI.

Insulin-resistance in glycogen storage disease type Ia: linking carbohydrates and mitochondria?

BACKGROUND

Glycogen storage disease type I (GSDI) is an inborn error of carbohydrate metabolism caused by mutations of either the G6PC gene (GSDIa) or the SLC37A4 gene (GSDIb). GSDIa patients are at higher risk of developing insulin-resistance (IR). Mitochondrial dysfunction has been implicated in the development of IR. Mitochondrial dysfunction can demonstrate abnormalities in plama acylcarnitines (ACs) and urine organic acids (UOA). The aim of the study was to investigate the presence of mitochondrial impairment in GSDI patients and its possible connection with IR.

METHODS

Fourteen GSDIa, seven GSDIb patients, 28 and 14 age and sex-matched controls, were enrolled. Plasma ACs, UOA, and surrogate markers of IR (HOMA-IR, QUICKI, ISI, VAI) were measured.

RESULTS

GSDIa patients showed higher short-chain ACs and long-chain ACs levels and increased urinary excretion of lactate, pyruvate, 2-ketoglutarate, 3-methylglutaconate, adipate, suberate, aconitate, ethylmalonate, fumarate, malate, sebacate, 4-octenedioate, 3OH-suberate, and 3-methylglutarate than controls (p < 0.05). GSDIb patients showed higher C0 and C4 levels and increased urinary excretion of lactate, 3-methylglutarate and suberate than controls (p < 0.05). In GSDIa patients C18 levels correlated with insulin serum levels, HOMA-IR, QUICKI, and ISI; long-chain ACs levels correlated with cholesterol, triglycerides, ALT serum levels, and VAI.

DISCUSSION

Increased plasma ACs and abnormal UOA profile suggest mitochondrial impairment in GSDIa. Correlation data suggest a possible connection between mitochondrial impairment and IR. We hypothesized that mitochondrial overload might generate by-products potentially affecting the insulin signaling pathway, leading to IR. On the basis of the available data, the possible pathomechanism for IR in GSDIa is proposed.

Safety and Efficacy of Chronic Extended Release Cornstarch Therapy for Glycogen Storage Disease Type I

BACKGROUND

Glycogen storage disease type I (GSD I) causes severe hypoglycemia during periods of fasting since both glycogenolysis and gluconeogenesis are impaired. Primary treatment in North America consists of cornstarch therapy every 3-4 h. Waxy maize extended release cornstarch was introduced for maintaining overnight glucose concentrations, but no studies have assessed long-term safety and efficacy of the product.

OBJECTIVE

To demonstrate the safety and efficacy of modified cornstarch in GSD I.

DESIGN

An open-label overnight trial of extended release cornstarch was performed. Subjects with a successful trial (optimal metabolic control 2 or more hours longer than with traditional cornstarch) were given the option of continuing into the chronic observational phase. Subjects were assessed biochemically at baseline and after 12 months.

RESULTS

Of the 106 subjects (93 GSD Ia/13 GSD Ib), efficacy was demonstrated in 82 patients (88%) with GSD Ia and 10 patients (77%) with GSD Ib. The success rate for extending fasting was 95% for females and 78% for males. Of the patients who entered the longitudinal phase, long-term data are available for 44 subjects. Mean duration of fasting on traditional cornstarch prior to study for the cohort was 4.1 and 7.8 h on the extended release cornstarch (P < 0.001). All laboratory markers of metabolic control have remained stable in the chronically treated patients.

CONCLUSION

Extended release cornstarch appears to improve the quality of life of patients with GSD I without sacrificing metabolic control. Avoiding the overnight dose of cornstarch should enhance safety in this population.

Investigation and management of the hepatic glycogen storage diseases

The glycogen storage diseases (GSD) comprise a group of disorders that involve the disruption of metabolism of glycogen. Glycogen is stored in various organs including skeletal muscle, the kidneys and liver. The liver stores glycogen to supply the rest of the body with glucose when required. Therefore, disruption of this process can lead to hypoglycaemia. If glycogen is not broken down effectively, this can lead to hepatomegaly. Glycogen synthase deficiency leads to impaired glycogen synthesis and consequently the liver is small. Glycogen brancher deficiency can lead to abnormal glycogen being stored in the liver leading to a quite different disorder of progressive liver dysfunction. Understanding the physiology of GSD I, III, VI and IX guides dietary treatments and the provision of appropriate amounts and types of carbohydrates. There has been recent re-emergence in the literature of the use of ketones in therapy, either in the form of the salt D,L-3-hydroxybutyrate or medium chain triglyceride (MCT). High protein diets have also been advocated. Alternative waxy maize based starches seem to show promising early data of efficacy. There are many complications of each of these disorders and they need to be prospectively surveyed and managed. Liver and kidney transplantation is still indicated in severe refractory disease.