© 2002 by the American Diabetes Association, Inc.
Delayed Gastric Emptying and Gastric Autoimmunity in Type 1 Diabetes
1 Department of Endocrinology-Diabetology, Faculty of Medicine, University of Antwerp, University Hospital Antwerp, Edegem, Belgium
OBJECTIVEDelayed gastric emptying and/or gastrointestinal symptoms occur in 3050% of diabetic patients. Known contributing factors are autonomic neuropathy and acute hyperglycemia, but the role of gastric autoimmunity has never been investigated, although 1520% of type 1 diabetic patients exhibit parietal cell antibodies (PCAs). We studied gastric motility in diabetes in relation to PCA status, autonomic nerve function, HbA1c, thyroid-stimulating hormone (TSH), Helicobacter pylori (HP), acid production, and gastric histology. RESEARCH DESIGN AND METHODSGastric emptying of solids and liquids (measured by 13C-octanoic acid and 13C-glycine breath tests, respectively) was tested in euglycemic conditions in 42 type 1 diabetic patients (male/female: 29/13; 15 PCA+; mean age 40 ± 15 years; mean HbA1c 7.8 ± 0.9%). Gastrointestinal symptoms, autonomic nerve function (Ewing tests), PCA status (indirect immunofluorescence), gastric histology, and acid secretion (pentagastrin) were assessed. RESULTSSolid gastric emptying was delayed in 40% and liquid emptying in 36% of patients. Gastric motility did not correlate with symptoms. PCA status, gastric morphology, and acid secretion were similar in those with and without gastroparesis. HbA1c level (ß = 1.34, P = 0.011) was the only risk factor for delayed solid emptying in a logistic regression model testing HbA1c, autonomic nerve function, PCA, HP status, age, sex, diabetes duration, and TSH. Half-emptying time for liquids correlated with TSH level (r = 0.83, P < 0.0001) and autonomic neuropathy score (r = -0.79, P = 0.001).
CONCLUSIONSWe found that
Abbreviations: CAN, cardiovascular autonomic neuropathy CV, coefficient of variation fT4, free T4 GEC, gastric emptying coefficient HP, Helicobacter pylori PCA, parietal cell antibody t1/2, gastric half-emptying time TSH, thyroid-stimulating hormone
As many as 3050% of type 1 diabetic patients have evidence of delayed gastric emptying, a dysfunction that may be manifested in gastrointestinal symptoms and/or metabolic instability (14). Conversely, many patients with gastroparesis are asymptomatic, and subjects with symptoms may have normal gastric emptying (4,5). Diabetic gastroparesis comprises a decrease in fundic and antral motor activity (68), a reduction in or lack of the interdigestive migrating motor complex (8), gastric dysrhythmias (9), and "pylorospasms" (10). The etiology of diabetic gastroparesis is still not fully established, but important factors seem to be autonomic neuropathy (6,1113), acute hyperglycemia (14,15), and abnormalities of gut hormones and neurotransmitters, such as motilin (16), gastrin (17), and nitric oxide (18). Thyroid function (19), gastric acid secretion (20,21), or Helicobacter pylori (HP) infection (22) may also modulate gastrointestinal motility. However, the role of gastric autoimmunity in diabetic gastroparesis has never been investigated, although 1520% of type 1 diabetic patients exhibit parietal cell antibodies (PCAs) (23), which, by impairing acid secretion (24,25), may modify gastric motility. Because treatment is possible (1,2,26), diagnosing and identifying risk factors for gastroparesis is important for controlling symptoms and enhancing glucoregulation. We examined the prevalence of delayed gastric emptying, under euglycemic conditions, in type 1 diabetic patients in relation to PCA status, cardiovascular autonomic function, HbA1c, HP status, thyroid function, acid production, gastrin levels, and gastric histology. The relationship between gastric emptying and gastrointestinal symptoms was also evaluated. We are one of the first to perform the 13C-octanoic acid breath test (13,27,28) and the first to use the 13C-glycine breath test for solid and liquid emptying, respectively, in diabetic patients.
Patients We studied 42 euthyroidic type 1 diabetic patients, comprising 15 PCA+ and 27 PCA- subjects (male/female 29/13; mean age 40 ± 15 years; mean diabetes duration 18 ± 9 years; mean HbA1c 7.8 ± 0.9%). The patients were consecutively recruited, regardless of gastrointestinal symptoms, from 69 PCA+ and 100 PCA- patients attending the Antwerp University Diabetes Clinic, and fulfilled criteria for type 1 diabetes (29). Patients with a history of gastric surgery or gastric outlet obstruction or who were taking motility-altering drugs, anti-inflammatory drugs, antacids, or proton pump inhibitors were excluded. Smoking, drinking beverages containing alcohol or caffeine, and strenuous exercise were prohibited in the 24 h before the gastric emptying tests. The local ethics committee approved the study, and each patient gave written informed consent.
Methods
Gastrointestinal symptoms.
Autonomic nerve function.
Helicobacter pylori. At upper gastrointestinal endoscopy (Olympus Videoscope GIF/Q140; Melville, NY), at least two biopsies from fundus, corpus, antrum, and descending duodenum were taken. Then, two investigators evaluated 5-µm sections, unaware of the patients clinical and laboratory findings. The visual analog scale of the updated Sydney system was used to evaluate inflammation, activity, atrophy, intestinal metaplasia, and HP colonization (32). HP immunostaining was performed by standard procedures using a polyclonal rabbit HP IgG antibody (Dako B0471; Dako, Glostrup, Denmark; dilution 1/200).
Gastric acid secretion.
Gastric emptying
13C octanoic acid breath test (solids)
13C-glycine breath test (liquids) Good-to-excellent correlations between the GEC and the scintigraphic half-emptying time (r = 0.74 for liquids, r = 0.88 for solids) and between the t1/2 determined by breath test and scintigraphy (r = 0.91 for liquids, r = 0.92 for solids) have been previously described (33,34).
Statistical analysis
Gastrointestinal symptoms were reported by 43% of patients, but the majority of patients had no or only mild symptoms, with a median symptom score of 4. Early satiety and abdominal bloating were present in 17 patients (33%), nausea and/or vomiting in 7 patients (17%), abdominal pain in 6 patients, and regurgitation and/or heartburn in 5 patients. No associations were noted between presence or score of symptoms and indexes of solid and liquid emptying (GEC and t1/2). Autonomic neuropathy was present in seven patients (three severe, two definite, and two borderline).
Parietal cell antibody findings
Solid gastric emptying Solid gastric emptying was delayed (GECbreathsolids <3.1, t1/2breathsolids >75') in 40% of type 1 diabetic patients. The mean glycemia during solid emptying was 119 ± 37 mg/dl. In this range, glycemia did not correlate with indexes of solid emptying (GEC and t1/2). However, patients with delayed solid emptying had higher HbA1c levels than those with normal solid emptying (P = 0.005) (Table 2). Autonomic neuropathy was equally common in both groups, and no association was observed between CAN score and rate of solid emptying. No differences were found in gastric histology (i.e., absence/presence of autoimmune gastritis), acid secretion parameters (basal, maximal, or peak acid output), or gastrin levels between those with and without gastroparesis. HbA1c level (ß = 1.34;P = 0.011) was the only independent risk factor for delayed solid gastric emptying in a logistic regression model testing HbA1c, autonomic nerve function, PCA, HP status, gastrin, TSH, age, sex, and diabetes duration. The t1/2breathsolid correlated strongly with GECbreathsolid (r = -0.81, P < 0.0001). Patients with delayed solid emptying tended to have a delay in liquid emptying (P = 0.1); furthermore, a correlation between t1/2breathsolid and t1/2breathliquid (r = 0.44, P = 0.037) was found. Solid and/or liquid emptying was delayed in 23 patients (55%).
Liquid gastric emptying Liquid gastric emptying was delayed (GECbreathliquids <3, t1/2breathliquids >55') in 36% of type 1 diabetic patients. The mean glycemia during liquid emptying was 129 ± 34 mg/dl. No correlations were observed between the level of glycemia and indexes of liquid emptying (GEC and t1/2). Although each subject was euthyroidic, patients with delayed liquid emptying had higher TSH levels (P = 0.02) than those with normal liquid emptying (Table 3). Further, a strong correlation was noted between t1/2breathliquid on one hand and TSH levels (r = 0.83, P < 0.0001), fT4 levels (r = -0.65, P = 0.021), and CAN score (r = -0.79, P = 0.001) on the other. However, logistic regression analysis could not identify a single independent risk factor for liquid gastric emptying when HbA1c, autonomic nerve function, PCA and HP infection status, gastrin and TSH levels, age, sex, and duration of diabetes were tested.
This study investigated the putative role of PCA, present in 1520% of type 1 diabetic patients (23), in the etiology of diabetic gastroparesis, using breath tests for liquid and solid emptying in euglycemic conditions. More than half of our type 1 diabetic patients (55%) had delayed gastric emptying (solids in 40% and liquids in 36%), in line with previous data (13). HbA1c level was identified as a risk factor for delayed solid emptying. Autonomic nerve function, PCA or HP status, gastric histology, acid secretion, or gastrin or TSH level did not seem to affect solid emptying. On the other hand, TSH level and autonomic neuropathy score correlated with t1/2breathliquid. Age, sex, and diabetes duration did not correlate with gastric emptying rate, supporting results from other studies (13,35,36). Breath tests have several advantages over scintigraphy, with which they correlate very well (see RESEARCH DESIGN AND METHODS). They are easy to perform, noninvasive, have good reproducibility, and avoid radiation burden, thereby facilitating emptying studies in fertile women and children (13,27,28,33,34). Moreover, many tests can be done simultaneously because 13CO2 can be analyzed overnight. Unlike a number of studies, ours controlled for many variables that may affect gastrointestinal symptoms and emptying: glucose level at the time of gastric emptying, gastric mucosal status, HP status, and autonomic nerve function. Most patients had no or only minor complaints, reflecting the fact that they were not selected on the basis of symptoms. We observed no association between gastric motility and symptoms, confirming some (7,37), but opposing other reports (4,13,38). In line with recent data (38), bloating was the most common symptom. Abnormalities in visceral sensation (39) or a variable degree of vagal afferent and efferent dysfunction (1) might explain the poor link between symptoms and gastric motility. Glycemic control may also influence the prevalence or perception of gastrointestinal symptoms (15,40), although this was not supported by our results. Gastric neuromuscular dysfunction may account for poor metabolic control, resulting from the dyssynchrony of insulin administration and emptying of nutrients (2,3). All our patients had good metabolic control. Nevertheless, we found that HbA1c levels were associated with delayed solid emptying, contrary to findings in other studies (12,13). It is not clear whether worse metabolic control determines or is determined by delayed gastric emptying. Prospective follow-up studies designed to see whether improving HbA1c would also improve gastric motility may help to clarify this interesting finding. Acute hyperglycemia may slow down gastric emptying (14,15) by evoking pyloric contractions (41) or suppressing antral contractions (42). In contrast, others found no link between glycemia and gastric motility (4,6). In euglycemic conditions, we did not see an effect of glucose levels on gastric emptying. Autonomic neuropathy with loss of vagal tone and increased sympathetic nervous system activity has been associated with gastric dysrhythmias (5,43). Years ago, Kassander (5) noted the similarity between clinical and radiographic findings of gastroparesis and gastric atony observed after surgical vagotomy. In addition, some (44), but not all (45), researchers have found histologic abnormalities in vagal nerve tissue of diabetic patients. We did not observe a link between CAN scores and rates of solid emptying, confirming results from some studies (4,27,37), but opposing results from other studies, describing a weak association (6,12,13). However, a good correlation was found with t1/2breathliquid. Perhaps these conflicting results are caused by differences in neuropathic involvement in solid and liquid emptying (4) or by differences in accuracy between classical CAN tests and the new ones using spectral and vector analysis (46). Our approach in which breath tests were performed on 2 days to avoid the use of 14C could also have introduced a source of variability. However, all tests were done in euglycemic conditions using standard procedures. Despite the poor relationship between emptying of solids and liquids (6,13), suggesting that predictors of delayed solid emptying differ from those of liquid emptying (38), we observed a weak correlation between t1/2breathsolid and t1/2breathliquid; in addition, patients with delayed solid emptying tended to have a delay in liquid emptying. Cyclic variation in gastric acid secretion, synchronous with the various phases of the migrating motor complex, have been shown in duodenal ulcer disease (21). Moreover, one group observed a delay in gastric emptying in patients with chronic atrophic gastritis and hypo- or achlorhydria (20). However, others have reported that interdigestive antroduodenal motility in achlorhydria is not different from that in normal acid-secreting control subjects (21). Our results support the observation that acid secretion is not essential in the regulation of gastric motility (47). Moreover, we did not observe a link between gastric motility and PCA positivity, the latter being associated with hypochlorhydria, or gastric histology. Furthermore, HP infection did not influence gastric emptying or the presence or severity of gastrointestinal symptoms (22). This is an important observation, because abnormal gastric emptying could affect urea breath test results. We and others have found no association between urea breath test and gastric emptying breath test results (22). Despite the fact that all patients were euthyroidic, we observed a strong correlation between t1/2breathliquid and TSH levels. Thus subclinical hypothyroidism may affect gastric motor activity, as does overt hypothyroidism (19). The pathogenesis of gastric motor hypoactivity is not precisely known. Autonomic neuropathy, disturbance of impulse conduction at the myoneural junction, changes in gastrointestinal peptide hormone metabolism, and autoimmune factors might explain this dysfunction. In conclusion, more than half of type 1 diabetic patients studied had a delay in gastric emptying that did not correlate with symptoms. Gastric autoimmunity did not contribute to diabetic gastroparesis. HbA1c level was the only independent risk factor for delayed solid emptying. Autonomic nerve function, PCA or HP infection status, age, sex, diabetes duration, gastric histology, gastrin levels, and acid secretion did not seem to affect solid emptying. On the other hand, TSH level and autonomic neuropathy score were correlated with t1/2breathliquid. It is important to report the lack of contribution of gastric autoimmunity to delayed gastric emptying and to propose an etiological role of HbA1c and subclinical hypothyroidism. It is hoped this work will stimulate new hypotheses and encourage the use of breath tests.
This study was supported by a grant from the European Foundation for the Study of Diabetes. The technique of the breath tests was introduced to the Department of Gastroenterology by Prof. Dr. Y. Ghoos and Dr. B. Geypens (Department of Gastroenterology, University Hospital Gasthuisberg, Leuven, Belgium). We gratefully acknowledge Dr. K. Van Acker and Dr. F. Peiffer (Department of Endocrinology-Diabetology) for their help in patient recruitment, Dr. C. Van Campenhout and K. Van Cotthem (Laboratory of Immunology and Protein Chemistry), Prof. Dr. E. Van Marck and Prof. Dr. J. Bogers (Department of Pathology), Prof. Dr. V. Van Hoof (Laboratory of Biochemistry), Apr. M. Martin (Laboratory of Hormonology), Prof. Dr. M. Ieven (Laboratory of Microbiology), B. Raeymaeckers and R. Borrie (Department of Gastroenterology), and Dr. B. Manuel y Keenoy, J. Vertommen, P. Aerts, S. Schrans, and M. Vinckx (Laboratory of Endocrinology-Diabetology) of the University of Antwerp. Parts of this study were presented at the 61st Scientific Sessions of the American Diabetes Association, Philadelphia, PA, June 2001.
Address correspondence and reprint requests to Christophe De Block, MD, Department of Endocrinology-Diabetology, Faculty of Medicine, University of Antwerp, University Hospital Antwerp, Wilrijkstraat 10, B-2650 Edegem, Belgium. E-mail: cdeblock{at}uia.ua.ac.be. Received for publication 2 August 2001 and accepted in revised form 7 February 2002. A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||