Prevalence of Diabetes on Santa Cruz Island in Galapagos Archipelago

This was an observational study offering a screening program for diabetes in a health clinic in Puerto Ayora town on Santa Cruz Island to determine the prevalence of this disorder and identify those at risk. A 1-month screening program was undertaken. Of 141 patients screened, 85% of men and 83% of women were overweight or obese; 16 (11%) had suspected undiagnosed diabetes and 22 (16%) were at high risk of developing diabetes. This is the first reported study of glucose intolerance prevalence in Galapagos. Urgent education and prevention programs are required to address this public health problem.


Objective
Diabetes mellitus is an increasing health problem, imposing a public health burden on health systems worldwide (1). The International Diabetes Federation (IDF) reports a prevalence of 6% (1 in 18 adults) in Ecuador and US $562.50 annual health care expenditure per person (2).
The onset of type 2 diabetes can be delayed or prevented; effective management reduces risk of complications. Self-management is the cornerstone of effective care (3). Our study was observational and offered a screening and education program for diabetes in a health clinic in the town of Puerto Ayora to determine prevalence of this disorder and identify those at risk.

Methods
The Galapagos archipelago, with a population of approximately 23,000 (48.2% female), is 1,000 km (621 miles) off Ecuador's coast. It consists of 20 islands (5 of which are inhabited) and 250 islets (4). Santa Cruz is the main island and has 61% of the population (approximately 14,000); 78% of the population live in the main town, Puerto Ayora. The age structure of the population on the island consists of 28% aged less than 15 years, 68% aged 15 to 64 years, and 4% aged 65 years or older(5).
Between October 31 and November 29, 2012, a diabetes screening program was offered in the Centro de Salud clinic in Puerto Ayora. The diabetes screening program was advertised weekly on the local television news channel, radio station, and on the Internet. For 1 day (November 14, 2012, National Diabetes Day) screening was offered at a stall set up in the local park by the port.
The International Expert Committee guidelines for diagnosis were used: fasting glucose 126 mg/dL or higher (≥7 mmol/L) for diagnosing diabetes and fasting glucose 100 to 125 mg/dL (5.6-6.9 mmol/L) for diagnosing high-risk individuals with impaired fasting glucose (IFG) (1,6). The committee's guidelines define highrisk individuals as adults whose body mass index (BMI) is 25 kg/ m 2 or higher with 1 or more of the following risk factors: physical inactivity, first-degree relative with diabetes, high risk race/ethnicity (African American, Latino, Native American, Asian American, Pacific Islander), hypertension 140/90 mm Hg or higher or undergoing therapy for hypertension, and history of cardiovascular disease. We used capillary blood glucose testing on a single finger prick test (7-9).
At presentation to the health clinic, data on the following personal demographics and physical measurements were collected: age, smoking status, personal history of diabetes, weight, height, fasting capillary glucose, and blood pressure. Glucose was tested with Contour test stripes using a Contour (Bayer) glucometer. Weight was measured on a Weigh Beam Eye-Level (Detecto Scale Company) scale (0-175 kg or 0-400 lb).
All patients were provided with education on nutrition and lifestyle changes. Patients with abnormal results were given advice about health concerns and information about improving their diet and increasing physical activity. Appointments were made for repeat testing within 1 to 2 weeks.
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Results
From 5 to 15 patients, including pediatric patients, presented themselves each day to the clinic for various health reasons and were invited to participate in the screening program. Patients were excluded if under the age of 18 years, pregnant, or had not fasted. In total, 141 patients were screened for fasting glucose, and 135 had their weight measured. Six patients refused to have their weight measured or were unable to be weighed (eg, in a wheelchair).
Of the 141 patients screened, 23 (16.3%) reported that they had previously been told they have diabetes. Of these, 9 were taking at least 1 medication: 6 were taking metformin; 1, sitagliptin; 1, glimepiride; and 2, glibenclamide. No patients were having regular follow-up on the mainland. Among patients who were not known to have diabetes, 16 had raised fasting glucose levels; 22 patients had IFG (Table 2). Therefore, within this screened population, 11.3% had a likely new diagnosis of diabetes and 15.6% were at high risk of developing diabetes in the future.

Discussion
Our findings suggest substantial numbers of people have undiagnosed, or are at high risk of developing, diabetes. These figures appear higher than those reported by IDF and World Health Organization for Ecuador, especially for the prevalence of obesity (2,10) (Appendix A). Obesity is strongly linked with diabetes risk (11). No published data was found on rates of exercise or hypertension in Galapagos.
Ecuador has close ties to the United States and may be sensitive to US economic, industrial, and cultural influences (12). Galapagos is heavily reliant on tourism, and with an annual population growth of 6.4%, may be at higher risk of increasing obesity (4). Landscape on the islands is not amenable to farming, and farming is carefully managed to protect endemic species. Similar situations have been noted in other island populations, such as the Pacific islands, with increasing prevalence of diabetes and obesity due to rapid population and economic growth and transition to westernization (13). Appendix B shows a comparison of data for diabetes and obesity for Ecuador and other island populations.
Limitations of this study are that it has a small sample size and high dropout rate for repeat checks. Caution should be used when extrapolating outside this population. Bias in sampling may have occurred because only those individuals motivated to seek health advice were screened. Our study may overestimate the prevalence of obesity, as it is unlikely to have data on the more physically active, such as fishermen or cruise ship employees.
Individuals with impaired fasting glucose or impaired glucose tolerance are at high risk for developing diabetes. For populations like that of the Galapagos Islands, which already has multiple risk factors for poor health, there is an urgent need for action. President Rafael Correa suggested introducing a new tax on junk food suppliers to try to address Ecuador's rapidly rising obesity rates (14).

5.
International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care 2009;32 (7) 14.