International Journal of Diabetes Mellitus
Volume 2, Issue 2 , Pages 95-100, August 2010

Sustained gains from a diabetes prevention program and the role of telephone support

  • James A. Dunbar

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • Corresponding Author InformationCorresponding author. Address: Greater Green Triangle University Department of Rural Health, Flinders and Deakin Universities, P.O. Box 423, Warrnambool, VIC 3280, Australia. Tel.: +61 (0) 3 5563 3315; fax: +61 (0) 3 5563 3144.
    • ,
  • Nathalie Davis-Lameloise

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • ,
  • Benjamin Philpot

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • ,
  • Prasuna Reddy

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • ,
  • Stephen Bunker

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • ,
  • Sami Heistaro

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
    • ,
  • Tiina Laatikainen

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • Department of Chronic Disease Prevention, National Institute for Health and Welfare, Helsinki, Finland
    • ,
  • Edward D. Janus

      Affiliations

    • Greater Green Triangle University Department of Rural Health, Flinders University, and Deakin University, Warrnambool, Australia
    • The Department of Medicine, University of Melbourne, Western Hospital, Footscray, Australia

Received 5 February 2010; received in revised form 29 March 2010; accepted 3 May 2010. published online 01 June 2010.

Article Outline

Abstract 

Background

An evaluation of the sustainability of lifestyle changes was undertaken for participants completing a 12month diabetes prevention program. This second part of the study also tested whether regular structured telephone calls could be effective in maintaining lifestyle changes.

Methods

Originally, 237 participants completed a 12month group-based lifestyle intervention study. They were aged 40–75years, with a moderate to high risk of developing type 2 diabetes. Participants were then randomised to telephone support (n=107) or self-care only (n=98) for 18months, and re-assessed using anthropometric, clinical, psychological and general health measures.

Results

A total of 164 participants (85 telephone support and 79 self-care only) completed the follow-up. Changes between 12 and 30months for the telephone support group were not significantly different from those found in the self-care only group. Beneficial lifestyle changes achieved by participants were generally sustained after the diabetes prevention program, with the exception of fasting plasma glucose and some psychological measures.

Conclusions

Positive outcomes achieved at 12months were generally maintained after a further 18months. Telephone support did not appear to produce additional benefits.

Keywords: Diabetes prevention, Telephone support, Lifestyle modification, Follow-up

 

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1. Introduction 

Type 2 Diabetes Mellitus (T2DM) is a major current health concern worldwide [1], [2]. The risk of developing T2DM is attributable to both environmental and genetic factors [1], but the recent increase in incidence seems to be mainly due to lifestyle factors, such as dietary habits and lack of physical activity [3]. In 2004–2005, about 700,000 Australians, or 3.6% of the population [4], were diagnosed with diabetes. About half of those who have diabetes are not aware of their condition [5]. Of those with diabetes, around 83% have type 2 (non-insulin dependent) diabetes [4]. It is estimated that about 10.6% of Australians may have pre-diabetes or impaired glucose tolerance [5], which is an early indicator for developing diabetes (about one in three will go on to develop type 2 diabetes).

In 2004–2006, the Greater Green Triangle University Department of Rural Health (GGT UDRH) developed a diabetes prevention program (GGT DPP) for use in Australian primary health care settings among English speaking groups [6]. The study provided evidence that a type 2 diabetes prevention program using lifestyle intervention is feasible in primary health care settings in Australia. Results at 12months included a mean weight reduction of 2.52kg and waist circumference by 4.17cm, and an imputed risk reduction for T2DM of 40%. There was also a reduction in fasting and 2-h glucose values.

The GGT DPP was based on the Finnish Diabetes Prevention Study (DPS) clinical trial [7] and the Good Ageing in Lahti Region (GOAL) Lifestyle Implementation Trial [8] which was conducted in a primary health care setting. Both of these interventions used a lifestyle behaviour change approach for those at high risk. The Finnish DPS showed a 58% relative risk reduction of T2DM after a mean intervention period of 3.2years [9]. The corresponding figure at a median of seven years total follow-up was 43% [10]. The GOAL Lifestyle Implementation Trial also reported sustainable results at 3years [11].

Components of an ideal ongoing program to sustain lifestyle changes achieved are yet to be determined. Recent studies evaluating use of the telephone as a primary method for delivering lifestyle and chronic disease management interventions have shown promising results [12]. The telephone has considerable and increasing potential: it is relatively inexpensive, widely available, not limited by geographical barriers, and is being increasingly adopted by large government and non-government organisations with the capacity to deliver large-scale interventions.

The hypotheses in this study were: (1) that gains achieved at 12months would be sustained at 30months and (2) that a continuing telephone support program with group facilitators would result in better maintenance of the measured outcomes 18months after completing the original 12month GGT DPP intervention.

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2. Materials and methods 

2.1. Design and recruitment of main intervention 

The GGT DPP was conducted in Victoria and South Australia in 2004–2006, using primary health care as a setting to reduce the progression to T2DM [6]. The Finnish Diabetes Risk Score (FINDRISC) tool [13] was used in general practice in three regions to identify patients at high risk of developing T2DM. On this scale, scores range from 0 to 26. A score of ⩾12 predicts the development of T2DM in more than one in six individuals within 10years. A minimum score of 12 was the main criterion for recruitment. The recruits were given an oral glucose tolerance test, and those who were found to already have diabetes were referred for treatment to their family doctors. The study participants included those with impaired fasting glucose and impaired glucose tolerance, as well as normoglycaemia. The intervention model used in this study, described in detail elsewhere [6], was based on the approach of the Finnish GOAL study [14]. The program consisted of six two-hour group sessions, the first five over eight weeks and the last delivered at 8months. A goal setting and planning approach was used to enhance behaviour change in physical activity and dietary habits. Regular self-assessment was used to empower participants to make personal short and long term goals, and create structured plans to achieve these. As in the Finnish study [10], five goals were targeted with these aims: (1) less than 30 percent of the total energy intake from fat, (2) less than 10 percent of total energy intake from saturated fat, (3) more than 15g of fibre/1000 calories, (4) more than 4h/week of moderate level physical activity and (5) more than five percent weight reduction.

In total, 311 individuals (88 men and 223 women) aged 40–75years were eligible to participate.

2.2. Randomisation 

According to facilitator records, 228 individuals were expected to complete the GGT DPP and be willing to participate in the follow-up. Participants within the session groups were pre-emptively divided equally, randomised into a group receiving telephone support and a group without telephone support (self-care), with 11 married couples kept together to limit contamination. Inclusion criteria for the follow-up required that participants complete the GGT DPP and not have pre-existing T2DM.

As the end of the GGT DPP overlapped with the beginning of the follow-up, participants expected to complete the GGT DPP were not necessarily the same as those who actually completed the GGT DPP. Of 311 individuals who began the original intervention, 237 attended both baseline and 12month health checks and at least one of the six sessions of the program (Fig. 1). After the initial randomisation of 228 individuals, seventeen not completing the GGT DPP and four diagnosed with T2DM at 12months were excluded. Another two who received the GGT DPP intervention despite being outside the age limit were also excluded. The remaining 205 were allocated to telephone support (n=107) and self-care only (n=98).

2.3. Telephone support follow-up 

The telephone support group received regular calls from specially trained nurses, mainly recruited from the original GGT DPP [6], supervised by a clinical health psychologist with experience in chronic disease management and T2DM intervention programs. Calls followed a semi-structured interview. The questionnaire referred to by the nurses contained the personal goals (physical activity and diet) that had been set at the end of the 12month intervention, and specific questions on achievement, compliance, and difficulties encountered. Nurses recorded this information, and gave advice and encouragement towards achieving and maintaining these goals. If necessary, support materials were sent to participants, or they were referred to a relevant support service when stress, anxiety or depression issues were detected. Participants were phoned 4weeks after completing the initial 12months GGT DPP, monthly for the next 5months, and bi-monthly for the subsequent 12months (maximum of 12 phone calls). Calls were expected to last approximately 15min, depending on the support required. The self-care groups were not contacted by study nurses during the follow-up until being invited to attend the 30month clinical tests.

2.4. Measurements 

Clinical measurements including height, weight, waist and hip circumference, and blood pressure measurements, were made by study nurses at the end of the 12month main intervention, as previously described [6], and the end of the 30months. Participants fasted overnight for a minimum of 8h before the blood tests. Fasting plasma glucose (FPG), 2h oral glucose tolerance test (2h-OGTT), total cholesterol, triglycerides and high density lipoprotein (HDL) cholesterol were analysed [6]. Use of lipid and blood pressure lowering medication was also recorded.

In addition, participants were assessed for psychological distress (Kessler 10 Psychological Distress Scale) [15] and depression (Hospital Anxiety and Depression Scale (HADS)) [16]. General health was assessed using the Short Form 36 (SF-36v2) [17] standardised to Australian population norms [18].

2.5. Statistical analyses 

Statistical analyses were performed using PASW Statistics (SPSS) Version 17. Percentages, means, standard errors (SE), and 95% confidence intervals are presented. To test differences between telephone support and self-care only groups, t-tests and chi-square tests were performed (Table 1). Analysis of covariance was used to adjust for gender differences between 12 and 30months (Table 2). To assess long term effects, all participants completing the original 12month GGT DPP and attending 30month clinical tests were included in intention-to-treat analyses. Men and women were analysed separately. Since no gender differences were found, results are presented for the combined sample (Table 3). Each analysis consisted of all available data, with a maximum of 9.9% missing (for mental component summary, Table 3).

Table 1. Mean (SE) difference between self-care participants (n=79) and telephone support participants (n=85) at baseline (demographics) and 12months (anthropometric and psychosocial).
Self-care (n=79)Telephone support (n=85)Differencep-value
Baseline
Gender (% male)n=27 (34.2%)n=19 (22.4%)11.82%0.092
Age (years)56.5 (0.9)57.1 (1.0)−0.59 (1.35)0.662
Education (years)12.2 (0.4)11.8 (0.5)0.40 (0.51)0.434

Beginning of telephone support
Systolic blood pressure (mmHg)130.6 (1.7)129.5 (1.7)1.06 (2.44)0.664
Diastolic blood pressure (mmHg)79.0 (1.0)78.0 (1.1)1.02 (1.51)0.498
Weight (kg)89.7 (2.2)88.5 (1.8)1.15 (2.80)0.683
BMI (kg/m2)32.1 (0.6)32.6 (0.7)−0.45 (0.96)0.641
Waist circumference (cm)100.0 (1.7)100.3 (1.3)−0.29 (2.10)0.889
Hip circumference (cm)111.8 (1.4)113.7 (1.4)−1.92 (2.03)0.346
2h-OGTT (mmol/L)6.03 (0.18)5.89 (0.16)0.14 (0.24)0.552
FPG (mmol/L)5.37 (0.06)5.29 (0.06)0.08 (0.08)0.337
Total cholesterol (mmol/L)5.42 (0.13)5.35 (0.10)0.08 (0.17)0.648
Triglycerides (mmol/L)1.85 (0.11)1.79 (0.13)0.06 (0.17)0.719
HDL-cholesterol (mmol/L)1.38 (0.04)1.46 (0.05)−0.07 (0.06)0.262
LDL-cholesterol (mmol/L)3.23 (0.12)3.11 (0.10)0.12 (0.15)0.435

K-10 score14.6 (0.8)14.3 (0.4)0.27 (0.89)0.759
HADS depression score2.22 (0.36)2.39 (0.28)−0.17 (0.45)0.709

SF-36 v2
Physical functioning49.0 (1.0)48.5 (1.0)0.46 (1.39)0.743
Role limitations physical48.4 (1.1)47.7 (0.9)0.72 (1.42)0.615
Bodily pain46.8 (1.3)45.1 (1.2)1.72 (1.76)0.331
General health50.5 (0.9)50.6 (0.7)−0.05 (1.15)0.969
Vitality51.1 (1.0)50.2 (0.8)0.91 (1.27)0.471
Social functioning48.5 (1.2)49.3 (0.9)−0.84 (1.52)0.579
Role limitation emotional46.2 (1.5)47.2 (1.2)−0.99 (1.88)0.599
Mental health49.3 (1.1)48.7 (0.9)0.60 (1.44)0.679
Physical component summary49.1 (1.0)48.1 (1.0)0.97 (1.36)0.477
Mental component summary48.6 (1.3)49.0 (1.0)−0.40 (1.64)0.810
Table 2. Mean (SE) changes in self-care and telephone support groups from 12 to 30months.
Self-care (n=79)Telephone support (n=85)Differencep-value
Systolic blood pressure (mmHg)2.25 (1.73)1.94 (1.54)0.31 (2.31)0.433
Diastolic blood pressure (mmHg)−0.03 (1.31)0.26 (0.96)−0.29 (1.61)0.865
Weight (kg)1.12 (0.53)1.13 (0.50)−0.01 (0.73)0.949
BMI (kg/m2)0.43 (0.19)0.40 (0.19)0.02 (0.27)0.988
Waist circumference (cm)0.32 (0.60)−0.90 (0.63)1.21 (0.87)0.419
Hip circumference (cm)0.64 (0.52)0.63 (0.50)0.00 (0.72)0.951
2h-OGTT (mmol/L)0.11 (0.22)0.31 (0.19)−0.20 (0.29)0.387
FPG (mmol/L)0.38 (0.05)0.41 (0.05)−0.03 (0.07)0.780
Total cholesterol (mmol/L)−0.22 (0.12)−0.15 (0.09)−0.07 (0.15)0.779
Triglycerides (mmol/L)−0.18 (0.09)−0.19 (0.07)0.01 (0.11)0.801
HDL-cholesterol (mmol/L)0.00 (0.02)−0.03 (0.02)0.03 (0.03)0.255
LDL-cholesterol (mmol/L)−0.12 (0.11)−0.02 (0.08)−0.09 (0.13)0.883

K-10 score0.10 (0.47)0.11 (0.57)−0.02 (0.75)0.924
HADS depression score0.65 (0.29)0.15 (0.29)0.50 (0.41)0.152

SF-36 v2
Physical functioning−1.29 (0.82)−0.34 (0.66)−0.95 (1.04)0.311
Role limitations physical−0.20 (0.98)0.09 (0.82)−0.29 (1.28)0.748
Bodily pain−1.17 (1.02)−0.18 (1.04)−0.99 (1.46)0.549
General health−1.37 (0.64)−0.59 (0.65)−0.78 (0.92)0.515
Vitality−1.00 (0.80)−0.73 (0.94)−0.28 (1.25)0.913
Social functioning0.66 (1.19)−0.98 (1.08)1.64 (1.60)0.644
Role limitations emotional0.06 (1.42)−1.43 (1.18)1.49 (1.84)0.649
Mental health−0.36 (1.05)−0.33 (1.12)−0.03 (1.53)0.959
Physical component summary−1.23 (0.89)0.05 (0.73)−1.29 (1.15)0.245
Mental component summary0.27 (1.23)−1.09 (1.21)1.36 (1.73)0.704
Table 3. Comparison of means (SE) at baseline, 12 and 30months and mean changes (95% CI) between baseline and 12, 12 and 30months and baseline and 30months (n=172).
0months12months30monthsChanges 0–12Changes 12–30Changes 0–30
Systolic blood pressure (mmHg)131.3 (1.3)130.3 (1.2)132.0 (1.2)−0.97 (−2.95, 1.01)1.68 (−0.55, 3.91)0.71 (−1.67, 3.10)
Diastolic blood pressure (mmHg)80.7 (0.8)78.5 (0.7)78.7 (0.8)−2.23 (−3.69, −0.77)⁎0.23 (−1.30, 1.77)−1.99 (−3.55, −0.44)⁎
Weight (kg)92.0 (1.4)89.3 (1.4)90.3 (1.4)−2.68 (−3.52, −1.85)⁎1.03 (0.33, 1.73)⁎−1.65 (−2.51, −0.79)⁎
BMI (kg/m2)33.3 (0.5)32.4 (0.5)32.7 (0.5)−0.98 (−1.28, −0.68)⁎0.38 (0.12, 0.64)⁎−0.60 (−0.91, −0.28)⁎
Waist circumference (cm)104.5 (1.0)100.5 (1.0)100.4 (1.1)−3.95 (−4.74, −3.16)⁎−0.18 (−1.03, 0.66)−4.13 (−5.05, −3.21)⁎
Hip circumference (cm)115.4 (1.0)112.8 (1.0)113.4 (1.0)−2.62 (−3.31, −1.93)⁎0.63 (−0.07, 1.32)−2.00 (−2.79, −1.20)⁎
2h-OGTT6.66 (0.13)6.01 (0.13)6.27 (0.17)−0.65 (−0.90, −0.39)⁎0.26 (−0.02, 0.54)−0.39 (−0.69, −0.08)⁎
FPG5.51 (0.04)5.35 (0.04)5.75 (0.04)−0.15 (−0.22, −0.08)⁎0.39 (0.32, 0.47)⁎0.24 (0.17, 0.31)⁎
Total cholesterol5.64 (0.08)5.39 (0.08)5.22 (0.07)−0.25 (−0.38, −0.13)⁎−0.17 (−0.31, −0.03)⁎−0.42 (−0.57, −0.27)⁎
Triglycerides1.94 (0.08)1.80 (0.08)1.63 (0.07)−0.14 (−0.26, −0.03)⁎−0.18 (−0.28, −0.07)⁎−0.32 (−0.44, −0.20)⁎
HDL-cholesterol1.35 (0.03)1.42 (0.03)1.40 (0.03)0.07 (0.03, 0.10)⁎−0.02 (−0.05, 0.01)0.05 (0.01, 0.08)⁎
LDL-cholesterol3.41 (0.08)3.17 (0.08)3.12 (0.07)−0.25 (−0.36, −0.14)⁎−0.05 (−0.18, 0.08)−0.30 (−0.42, −0.17)⁎

K-10 score15.0 (0.4)14.2 (0.4)14.3 (0.5)−0.76 (−1.36, −0.16)⁎0.09 (−0.62, 0.81)−0.66 (−1.40, 0.07)
HADS depression score2.82 (0.23)2.33 (0.23)2.77 (0.25)−0.49 (−0.87, −0.10)⁎0.44 (0.04, 0.83)⁎−0.05 (−0.43, 0.33)

SF-36 v2
Physical functioning47.9 (0.6)48.7 (0.7)48.1 (0.7)0.84 (−0.23, 1.91)−0.68 (−1.69, 0.32)0.16 (−0.99, 1.31)
Role limitations physical47.6 (0.7)47.9 (0.7)47.9 (0.7)0.30 (−1.12, 1.72)0.00 (−1.25, 1.25)0.30 (−1.20, 1.80)
Bodily pain43.4 (0.9)46.2 (0.9)45.4 (0.9)2.81 (1.13, 4.49)⁎−0.86 (−2.27,0.55)1.95 (0.22, 3.68)⁎
General health47.6 (0.6)50.2 (0.6)49.5 (0.6)2.57 (1.59, 3.56)⁎−0.72 (−1.58, 0.14)1.85 (0.82, 2.88)⁎
Vitality47.7 (0.7)50.7 (0.6)49.7 (0.7)3.01 (1.84, 4.18)⁎−0.95 (−2.12, 0.23)2.06 (0.74, 3.38)⁎
Social functioning49.1 (0.7)48.6 (0.8)48.4 (0.8)−0.41 (−1.87, 1.05)−0.24 (−1.75, 1.27)−0.65 (−2.04, 0.74)
Role limitations emotional46.7 (1.0)46.6 (1.0)46.1 (1.0)−0.12 (−2.21, 1.98)−0.53 (−2.26, 1.20)−0.65 (−2.50, 1.20)
Mental health47.1 (0.8)49.0 (0.7)48.6 (0.8)1.97 (0.65, 3.30)⁎−0.45 (−1.90, 0.99)1.52 (−0.02, 3.06)
Physical component summary46.9 (0.7)48.7 (0.7)48.0 (0.7)1.75 (0.60, 2.89)⁎−0.63 (−1.77, 0.50)1.11 (−0.22, 2.45)
Mental component summary47.5 (0.9)48.4 (0.9)48.0 (0.9)0.89 (−0.70, 2.48)−0.34 (−2.01, 1.34)0.55 (−1.05, 2.15)

⁎p<0.05.

2.6. Ethics 

Participants gave written consent. The study was approved by the Flinders University Clinical Research Ethics Committee (reference number 105/034) and registered as a clinical trial (ISRCTN38031372).

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3. Results 

Of 205 eligible participants, 164 completed the follow-up. Of these, 85 received telephone support (mean 6.6 calls, SD=2.8, mean length of call 20min) and 79 had self-care information only (Fig. 1). The self-care group had slightly more men than the telephone support group but otherwise the groups were well matched (Table 1).

Changes in outcome measures between 12 and 30months are shown separately for the telephone support and self-care groups in Table 2. Between group differences were not significant. Since the telephone support did not appear to impact on the outcome measures, this allowed the two groups to be combined for further analyses. In order to assess the longer term effects of the GGT DPP, all available data was utilised. This included four participants who had diagnosed T2DM at 12months, and four who had prematurely been considered as ‘dropped-out’ of the GGT DPP and therefore not been randomised.

Among the 172 participants who completed the 12month DPP intervention and attended the 30month clinical tests, improvements in anthropometric, blood pressure, and lipid variables apparent at 12months were generally maintained at 30months with some exceptions (Table 3).

Although weight increased by 1.03kg during the follow-up period (12–30months) there was still a 30month mean reduction of 1.65kg. Waist circumference decreased further during the follow-up and after 30months there was a mean reduction of 4.13cm. Decrease in 2h-OGTT during the first 12months attenuated during follow-up, but at 30months was still significantly better (0.39mmol/L) than baseline. In contrast, FPG, which improved during the original 12month study, increased during follow-up, and was 0.24mmol/L higher at 30months than baseline.

Triglycerides and total cholesterol showed further improvement. This resulted in overall reductions of 0.32 and 0.42mmol/L, respectively.

After commencement of the initial 12month intervention, 12 participants started medication for dyslipidemia (n=5 during the GGT DPP and n=7 during the follow-up) and 10 for hypertension (n=2 during the GGT DPP and n=8 during the follow-up). When these are excluded, there is a slight increase in systolic blood pressure during follow-up. Also the further reduction between 12 and 30months in total cholesterol was no longer evident.

The impact on psychological measures was mixed. Depression scores improved during the initial 12month intervention but subsequently regressed to baseline. Also the statistically significant effect on psychological distress diminished during follow-up so that at the end the effect was no longer statistically significant. Positive effects observed on bodily pain, general health and vitality were maintained during follow-up. Mental health and physical composite scores regressed toward baseline. All other measures of health were unchanged during the follow-up.

Of the 237 participants who completed the original GGT DPP, a comparison between 30month clinical test attendees (n=172) and non-attendees (n=65) was undertaken. At beginning of follow-up (i.e. 12months after commencing initial intervention) no differences were found in demographics, anthropometric or clinical measurements, but non-attendees had worse physical functioning at 12months when compared with attendees (data not shown).

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4. Discussion 

The present study suggests that gains achieved at 12months during the GGT DPP [6], in a primary health care setting, can be sustained over the following 18months. Telephone support did not significantly improve the sustainability of the original intervention. Our results will inform further studies investigating the best ways to provide ongoing support to participants, which remains an important focus for those conducting diabetes prevention programs.

The success of the main intervention relied on the theories of behaviour change that were used. The theoretical framework of this intervention was based on the Health Action Process Approach (HAPA) [19] and on self-regulation theory [20]. The HAPA model incorporates a two-stage model with distinct phases for motivation formation and action. Alongside the HAPA model, self-regulation theory helps participants formulate goals and find strategies to achieve these goals through the difficult process of planning preparation and initiation of intended behaviour change action [21].

Participants involved in the 12month intervention were guided to plan how they would start achieving their behaviour changes. They were encouraged to incorporate the basic principles and appropriate skills into daily life in order to choose and plan concrete, positive, attainable and evolving goals that could be sustained and achieved in the long term. Participants set personal goals such as ‘eat more fruit and vegetables’, ‘have healthier snacks ready’ or ‘walk around the block with the dog’.

When participants agreed to continue the study with or without 18month telephone support follow-up, they were able to: acknowledge that they were at risk of type 2 diabetes, learn that the disease can be prevented by lifestyle changes, gain confidence in their ability to change, decide to change, plan where, when and how to make changes, learn how to avoid barriers and use resources, and learn how to recover from relapses.

Prevention programs demonstrate substantial benefits of healthy lifestyle changes in reducing risk of developing T2DM [10], [22], [23], [24]. The GGT DPP lifestyle intervention study achieved results comparable with earlier clinical trials [23], [24], [25]. For successful chronic disease programs, sustained effects are of major interest. Some weight loss and smoking cessation programs have shown loss of benefits in the long term, such as regaining weight, sometimes higher [26] than the initial weight, or reversion to smoking [27].

In the present study, outcomes of particular interest included physical (weight, waist and hip circumference, and blood pressure) and biochemical (total, LDL- and HDL-cholesterol, triglycerides, FPG, and 2h-OGTT) measurements at 30months. Almost all improvements shown at 12months were sustained at 30months with the main exception of FPG. Although weight increased during follow-up, overall it remained significantly lower than baseline, and reduction in waist circumference was maintained. The reduction in waist circumference is of major importance because central adiposity is the main driver of metabolic abnormalities that lead to type 2 diabetes [28]. Improvements in diastolic blood pressure and lipids, especially triglycerides, were maintained.

Fasting and 2h glucose were lower at 12months than at baseline, both rebounding by 30months, especially fasting glucose. This observation in those at high risk of diabetes parallels findings in the United Kingdom Prospective Diabetes Study (UKPDS) [29]. Those treated for established T2DM (usually with medication) initially had improved glycaemic control, but declined progressively over time. The effect is much like setting the clock back and slowing the progression of the beta islet cell failure.

No significant differences in mean outcome measures were found between the groups, with and without telephone support. As an extension of the GGT DPP, telephone counseling aimed primarily at supporting participants in sustaining the benefits already achieved, rather than to facilitate further improvement. Additionally, the self-care group showed continuing benefits of the original 12month intervention. Consequently, it is likely that our sample size was not large enough to determine the true effect of the telephone support.

During telephone support calls, enablers and barriers were discussed with participants, and actions taken such as referral to GP or counselor when needed. In general, the nurses reported a lack of new issues to discuss with participants. Although 12 telephone calls were scheduled, participants received an average of 6.6 calls. Some of those allocated to telephone support declined calls (n=16). Excluding these individuals had minimal effect on results (data not shown). For others, length of calls decreased over time, and participants who received more calls tended to have worse mental health and cholesterol, and better physical functioning. Telephone support could not have alleviated physical problems, and it is likely that those who had already been successful in their lifestyle changes did not find much benefit in support. Others may have struggled with meeting their goals and accepted more calls, but required more than was offered by the telephone support. The social support offered by the telephone calls may have also been a substitute for support obtained in the GGT DPP group sessions.

Email was considered as an alternative to telephone communication. However, this appeared less appropriate with an older age group from a rural area, with poor access to the internet, and preference for more personalised verbal communication.

Whilst evidence supporting efficacy of the telephone as a primary intervention method to deliver physical activity and dietary behaviour change interventions is promising, effects on outcomes measured have been mainly short-term with very few significant reductions reported for body mass index (BMI), lipids or blood pressure [12]. Additionally, studies on its use in diabetes management have not demonstrated effectiveness for sustaining lifestyle changes post-intervention [30].

The major strength of this study is that it has been successfully implemented within a primary care setting and reports sustainability of a group-based diabetes prevention program over 18months of follow-up. There were some dropouts. However, these individuals were similar at 12months to those attending 30month clinical testing. Also, in a small community, the likelihood of cross-contamination is increased, and we have no information regarding further contact between the participants.

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5. Conclusions 

In conclusion, this group-based prevention program in a primary health care setting, for individuals at high risk of T2DM, results in good initial outcomes which are sustained at 30months. Although providing telephone support on completion of the initial 12month intervention did not appear to produce additional benefits, further investigations into optimising ongoing support for these individuals remains an important issue.

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Conflict of interest 

None declared.

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Acknowledgements 

We thank Prof. J. Best and Mr. K. McNamara for advice during manuscript preparation, Prof. E. Vartiainen and Dr. P. Absetz for advice on project design, Ms. A. Chapman, Mrs. A. Kao-Philpot, and nurses involved in the follow-up, and Dr. M. Whiting and Ms. R. Tirimacco of SA Pathology (Flinders Medical Centre) for laboratory analysis. This study was funded by the Ray and Joy Uebergang Foundation, Warrnambool, Australia.

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PII: S1877-5934(10)00024-X

doi:10.1016/j.ijdm.2010.05.002

International Journal of Diabetes Mellitus
Volume 2, Issue 2 , Pages 95-100, August 2010

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