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The source of starch may interfere with glycaemic control in dogs, but few studies have evaluated these aspects in diabetic dogs. This study compared the effects of two isonutrient diets with different starch sources, peas and barley (PB) v. maize (Mi), on diabetic dogs. The Mi diet was processed in order to generate a lower starch gelatinisation index. In all, fifteen adult diabetic dogs without other conditions were included. The animals were fed two dry extruded rations with moderate levels of fat and starch and high levels of protein and fibre using a random, double-blind cross-over design. Glycaemic curves over 48 h were developed via continuous glucose monitoring after 60 d on each diet and with the same neutral protamine Hagedorn (NPH) insulin dosage. The following were compared: fasting, mean, maximum and minimum blood glucose, maximum and minimum glycaemia difference, glycaemic increment, area under the glycaemic curve, area under the glycaemic increment curve and serum fructosamine concentration. Paired t tests or Wilcoxon signed-rank tests were used to compare the amount of food and nutrients ingested and the dietary effects on glycaemic variables between the diets. Dogs fed the PB diet presented a lower average mean interstitial glucose (P=0·01), longer mean hypoglycaemic time (P<0·01), shorter mean hyperglycaemic time (P<0·01) and smaller difference between maximum and minimum blood glucose levels (P=0·03). Thus, the processing applied to the Mi diet was not sufficient to achieve the same effects of PB on glycaemic control in diabetic dogs.

The present study compared the intravenous glucose tolerance test (IVGTT) and the glucose postprandial response (GPPR) test for the evaluation of glucose metabolism in obese dogs. A total of ten owned obese dogs (body condition score (BCS) of 9; fat mass, 45.7 (sem 1.51) %) were used. These dogs had their weight reduced by 20 % (BCS, 8; fat mass, 33.5 (SEM 1.92) %; P < 0.001), designated as weight-reduced (WR) group. A control group of ten Beagle dogs was also included (BCS, 4.5; fat mass, 18.3 (SEM 1.38) %; P < 0.01). Glucose tolerance was measured by two methods: IVGTT (infusion of 0.5 g of glucose/kg body weight) and GPPR (consumption of cooked rice to achieve 6 g of starch/kg body weight). When using the IVGTT, the area under the curve (AUC) for glucose and maximum glycaemia were higher for obese dogs compared with controls (P < 0.05), with intermediate results for the WR group (P>0.05). Basal insulin, insulin response peak, insulinogenic index and the AUC for insulin increment from 0 to 15 min and from 60 to 120 min were higher for the obese group (P < 0.05), while the WR group and control dogs showed similar results (P>0.05). When using the GPPR test, the AUC for insulin increment from 0 to 120 min was higher for the obese group compared with the control group (P < 0.05) and intermediate for the WR group (P>0.05). However, the AUC for insulin increment from 120 to 360 min was similar between the obese and WR groups (P>0.05), while it was lower for the control group (P < 0.05). The IVGTT showed that the loss of 20 % body weight resulted in an improvement of glucose control with reduced insulin secretion, and these same WR dogs showed higher insulin secretion with values similar to those of obese dogs when the GPPR test was used.