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JOURNAL: Diabetes Care. 2004;27:436-440
AUTHORS: Dr. Ludvik
ABSTRACT: Caiapo has beneficial effects on the plasma glucose and cholesterol levels of patients with type 2 diabetes, according to the results of a randomized, double-blind, placebo-controlled trial.
COMMENTARY: Caiapo is a nutraceutical made from the extract of a variety of white sweet potato (Ipomoea batatas) that has been eaten raw in Japan for treatment of anemia, hypertension, and diabetes.
Bernhard Ludvik, MD, and colleagues from the University of Vienna in Austria selected 61 clinically stable type 2 diabetic patients. Subjects discontinued antidiabetic medication and followed a weight-maintaining diet (28-32 kcal/kg of body weight) consisting of 55% carbohydrates, 30% fat, and 15% proteins.
Patients were allowed to continue drinking alcohol and smoking cigarettes, although in limited amounts. Investigators advised subjects to maintain usual physical activity at a constant level throughout the study period.
The researchers divided patients into two groups: group 1 (n = 30) consumed Caiapo 4 g/day, and group 2 (n = 31) consumed placebo. Patients took Caiapo or placebo orally once daily, in the morning before breakfast. Data from both groups showed no differences at baseline except for glucose levels measured two hours after dinner.
The investigators administered a 75 g oral glucose tolerance test (OGTT) at baseline and after one, two, and three months. Fasting and two-hour glucose levels were measured from venous samples by the glucose oxidase method. Patients measured their blood glucose levels at home using a blood glucose test system three times per week: Monday before breakfast, Wednesday two hours after beginning lunch, and Friday two hours after beginning dinner. The investigators also measured HbA1c, cholesterol, and triglyceride levels.
After months 2 and 3, HbA1c levels significantly decreased in the Caiapo group (from 7.21% ± 0.15% at baseline to 6.94% ± 0.14% at two months and 6.68% ± 0.14% at three months; P < .05) compared with no change in the placebo group (P = .08 after two months and P = .23 after three months). At months 2 and 3, HbA1c values in the Caiapo group were lower than those in the placebo group (P < .0001).
Fasting blood glucose levels decreased in the Caiapo group (143.7 ± 1.9 mg/dL vs. 128.5 ± 1.7 mg/dL; P < .001) and did not change in the placebo group (144.3 ± 1.9 mg/dL vs. 138.2 ± 2.1 mg/dL; P = .052). The investigators observed a decrease in body weight in both the placebo group (P = .0027) and in the Caiapo group (P < .0001).
Body weight was linked to improvement in glucose control in the Caiapo group (r = 0.618; P < .0002). Two-hour glucose levels decreased significantly in the Caiapo group (193.3 ± 10.4 mg/dL vs. 162.8 ± 8.2 mg/dL) compared with the placebo group (191.7 ± 9.2 mg/dL vs. 181.0 ± 7.1 mg/dL; P < .001).
The investigators also found significantly lower levels of mean cholesterol in the Caiapo group at the end of treatment (214.6 ± 11.2 mg/dL) than in the placebo group (248.7 ± 11.2 mg/dL; P < .05). They did not observe significant changes in triglyceride levels or blood pressure. Caiapo was well tolerated without significant adverse effects.
"This study confirms the beneficial effects of Caiapo on fasting and postprandial plasma glucose levels, as well as on cholesterol, in patients with type 2 diabetes," they write. "For the first time, we demonstrated the long-term efficacy of Caiapo on glucose control by the observed reduction of HbA1c."