Gastric emptying, diabetes, and aging

The antroduodenal transition time is prolonged in adults with type 1 diabetes

BACKGROUND

The gastroparetic syndrome encompasses antral hypomotility, gastric dysrhythmia, impaired antroduodenal coordination, pyloric dysfunction, and abnormal duodenal motility; the last three collectively referred to as pylorospasms. We hypothesized that antroduodenal motility is diminished and transition time is prolonged in adults with type 1 diabetes (T1D) and polyneuropathy.

METHODS

This cross-sectional study included 124 participants, of which 21 were healthy, 53 had T1D and 50 had T1D with distal symmetrical polyneuropathy (T1D + DSPN). We used the wireless motility capsule to assess antroduodenal transition time, gastric emptying time, gastric and small bowel motility indices (MI), and numbers of alkalic/acidic exposures.

RESULTS

In comparison with controls, patients with T1D had prolonged antroduodenal transition time (1.85±1.5 vs. 6.6±4.8 minutes; p=0.02), which was even more pronounced in patients with T1D+DSPN (1.85±1.5 vs. 17.8±28.5 minutes; p<0.008. T1D+DSPN tended to have diminished gastric MI (11.9±2.4 vs. 12.7±1.0, p=0.07) and small bowel MI (13.1±1.4 vs. 13.6±0.6, p=0.05) and experienced more antral/pyloric alkalic episodes (1.2±1.3 vs. 2.0±2.1, p=0.02) compared with controls.

CONCLUSION

The current method may assess a proxy for severity of pylorospasms in patients with diabetes and other diseases associated with upper gastrointestinal motility disorders, which ultimately may optimize future management.

Insulin and incretin hormone responses to rapid versus slow ingestion of a standardized solid breakfast in healthy subjects

People with repeated rapid meal ingestion have been reported to have increased risk of insulin resistance, impaired glucose tolerance and obesity. To explore whether speed of eating a breakfast influences the postprandial rise of glucose, insulin and the incretin hormones, 24 healthy subjects (12 men and 12 women, mean age 62 years) ingested a standardized solid breakfast consisting of 524 kcal (60% from carbohydrate, 20% from protein, 20% from fat) over 5 or 12 minutes on separate days in random order. Breakfast ingestion increased circulating glucose and insulin with maximal levels seen at 30 minutes after start of meal ingestion with no significant difference in the two tests. Similarly, breakfast increased circulating levels of total (reflecting secretion) glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) with, again, no difference between the tests. Furthermore, gastric emptying, as revealed by the indirect paracetamol test, did not differ between the tests. We therefore conclude that the speed of breakfast ingestion does not affect the postprandial rise of glucose, insulin or incretin hormones in healthy subjects.

Changes in cardiovascular performance, biochemistry, gastric motility and muscle temperature induced by acute exercise on a treadmill in healthy military dogs

Changes in physiological parameters that are induced by acute exercise on a treadmill in healthy military dogs have not been thoroughly investigated, especially with regard to age. This study investigated the effects of acute exercise on a treadmill on cardiovascular function, biochemical parameters and gastric antral motility in military dogs. Thermography was used to assess variations in superficial hindlimb muscle temperature. Nine healthy dogs were distributed into three groups according to their age (Group I: 25 ± 7 months; Group II: 51 ± 12 months; Group III: 95 ± 10 months) and sequentially subjected to running exercise on a treadmill for 12 min (3.2 km/h at 0° incline for 4 min, 6.4 km/h at 0° incline for 4 min and 6.4 km/h at 10° incline for 4 min). Heart rate, systolic and diastolic arterial pressure (DAP), gastric motility, haematocrit and biochemical analyses were performed at rest and after each session of treadmill exercise. Infrared thermographic images of muscles in the pelvic member were taken. Exercise decreased DAP in Group I, increased systolic arterial pressure in Groups II and III and increased mean arterial pressure in Group III (all p < 0.05). After the exercise protocol, plasma creatine kinase and aspartate aminotransferase levels increased only in Group I (p < 0.05). Exercise increased heart rate and decreased the gastric motility of a solid meal at 180 min in all groups (all p < 0.05). Exercise also elevated temperature in the femoral biceps muscles in Group I compared with the older dogs. The results indicate that acute exercise decreased gastric motility in dogs, regardless of age, and caused more pronounced cardiovascular changes in older dogs than in younger dogs. Acute exercise also altered biochemical parameters and superficial hindlimb muscle temperature in younger military dogs.

Postprandial hypotension is associated with more rapid gastric emptying in healthy older individuals

BACKGROUND

Postprandial hypotension (PPH) occurs frequently in older individuals with disease and/or living in residential care, but its prevalence in "healthy" older individuals has not been evaluated in large cohorts. PPH is associated with substantial morbidity and increased mortality; current management is suboptimal. Recent studies suggest that the magnitude of the postprandial fall in blood pressure (BP) is related to the rate of gastric emptying (GE), so that relatively more rapid GE may potentially be a risk factor for PPH. We aimed to determine the prevalence of, and evaluate the association of GE with PPH.

METHODS

A total of 88 healthy "older", community-dwelling residents (47 women, 41 men; age 71.0 ± 0.5 years) attended a clinical research laboratory on a single occasion. Individuals consumed a 300 mL drink containing 75 g glucose and 150 mg C(13)-acetate. Exhaled breath was obtained for analysis of (13)CO2 and calculation of the 50% GE time (T50). BP and heart rate were assessed with an automated device.

RESULTS

Eleven (12.8%) of 86 subjects had PPH (2 had diabetes and were excluded). GE was faster in subjects with PPH than the remainder of the group (T50 118.0 ± 9.4 vs 142.3 ± 4.6 minutes, P < .05).

CONCLUSIONS

We conclude the prevalence of PPH in a cohort of otherwise healthy "older" individuals is 12.8% and PPH is associated with relatively more rapid GE. Therapies that slow GE may be useful in the management of PPH.

Physiology of the ageing gut

PURPOSE OF REVIEW

This article will review the recent publications (over the last 1-2 years) concerning the effects of ageing on gastrointestinal function, with an emphasis on the motor and sensory function of the gut.

RECENT FINDINGS

Recent publications support earlier observations of an age-related selective decline in the number of cholinergic neurons in the enteric nervous system, but also reveal a progressive loss of interstitial cells of Cajal in the stomach and colon throughout adult life. These changes appear to have surprisingly little effect on gastrointestinal motor function in healthy ageing, although gut sensation is impaired and older individuals have an increased susceptibility to gastrointestinal complications of comorbid illnesses.

SUMMARY

Alterations in gut function with ageing have particular implications in the oesophagus, colon, and anorectum. Dysphagia, gastro-oesophageal reflux disease, constipation, and faecal incontinence are the most prevalent clinical manifestations. Older individuals are also susceptible to postprandial hypotension, in which altered cardiovascular responses to intestinal nutrient exposure are pivotal. Dysphagia, delayed gastric emptying, and constipation are increasingly being recognized as early features of Parkinson's disease, and frequently precede the neurological manifestations.

Effects of variations in duodenal glucose load on glycaemic, insulin, and incretin responses in type 2 diabetes

AIMS

Postprandial glucagon-like peptide-1 (GLP-1) secretion and the 'incretin effect' have been reported to be deficient in Type 2 diabetes, but most studies have not controlled for variations in the rate of gastric emptying. We evaluated blood glucose, and plasma insulin, GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) responses to intraduodenal glucose in Type 2 diabetes, and compared these with data from healthy controls.

METHODS

Eight males with well-controlled Type 2 diabetes, managed by diet alone, were studied on four occasions in single-blind, randomized order. Blood glucose, and plasma insulin, GLP-1, and GIP were measured during 120-min intraduodenal glucose infusions at 1 kcal/min (G1), 2 kcal/min (G2) and 4 kcal/min (G4) or saline control.

RESULTS

Type 2 patients had higher basal (P < 0.0005) and incremental (P < 0.0005) blood glucose responses to G2 and G4, when compared with healthy controls. In both groups, the stimulation of insulin and GLP-1 by increasing glucose loads was not linear; responses to G1 and G2 were minimal, whereas responses to G4 were much greater (P < 0.005 for each) (incremental area under the GLP-1 curve 224 ± 65, 756 ± 331 and 2807 ± 473 pmol/l.min, respectively, in Type 2 patients and 373 ± 231, 505 ± 161 and 1742 ± 456 pmol/l.min, respectively, in healthy controls). The GLP-1 responses appeared comparable in the two groups. In both groups there was a load-dependent increase in plasma GIP with no difference between them.

CONCLUSIONS

In patients with well-controlled Type 2 diabetes, blood glucose, insulin and GLP-1 responses are critically dependent on the small intestinal glucose load, and GLP-1 responses are not deficient.