88 women with gestational diabetes (46 for the intervention group and 42 for the control group) were in the arm.

The intervention group were included in the health-promoting lifestyle education program. The education program consisted of three 45-min sessions, which included a face-to-face lecture with the dissemination and presentation of written and visual materials. Each participant in the intervention group was given the Health-Promoting Lifestyle Booklet and the Diary of a Woman with GDM card. The booklet features all of the health-promoting practices (self-monitoring of blood glucose, nutrition, physical activity, stress, sleeping, smoking, self-care and breastfeeding). The Diary of a Woman with GDM card features the daily program that women should follow (the hours for main meals and snacks, insulin hours, etc.). The education and counseling were maintained through follow-up via phone for intervention group.

Primary outcome of women with GDM was their healthy lifestyle behaviours measured on the HPLP-II. This scale, developed by Walker et al. (1987) on the basis of Pender's health promotion model, measures the health-promoting behaviours associated with a health-promoting lifestyle. The scale was revised in 1996 and designated as HPLP-II (Walker et al. 1996). Bahar et al. (2008) tested the scale's validity and reliability in Turkish. The Cronbach's alpha internal consistency coefficient of the scale was found to be 0.92. Higher scores on the scale indicate a higher performance level of the determined health-promoting behaviours. The scale consists of 52 items under the six subscales of spiritual growth, nutrition, physical activity, health responsibility, interpersonal relations and stress management. The lowest and highest possible scores on the scale are 52 and 208, respectively.

Quality of life of the women was measured using the SF-36. This scale, developed by Ware in 1987, is globally referred to as SF-36, as this acronym has been commonly used in all studies since the development of the scale. SF-36 is a self-assessment scale, consisting of 36 questions under eight subscales: physical functioning, physical role limitation, social functioning, mental health, energy-vitality, bodily pain, general health perceptions and emotional role limitation (Ware & Sherbourne 1992). Pınar (1995) tested the scale's validity and reliability in Turkish. The Cronbach's alpha internal consistency value was found to be 0.91.When the scores of each subscale in the scale increase, health-related quality of life also increases. Subscales are all separately scored. "0" point indicates poor health and "100" points states good health (Ware and Sherbourne, 1992).

CES-D Scale was used to assess symptoms of depression in women. This short scale, developed by Radloff (1977) to measure depressive symptoms, can be administered to both the general population and specially selected groups. The CES-D consists of 20 items, each of which are scored between 0 and 3. The 4th, 8th, 12th, and 16th items are reversely scored. The total score ranges between 0 and 60, and a score of 16 and higher suggests the risk of depression, while lower scores on the CES-D Scale indicate decreased risks for depression. The scale measures symptoms experienced over the most recent week of time according to frequency of occurrence, where 0= Rarely or never, 1= Sometimes, 2= Often, and 3= Usually or always. Yilmaz (2010) tested the scale's validity and reliability in Turkish. The Cronbach's alpha value was found to be 0.85 for the entire scale.

Postpartum diabetes control of women with GDM was assessed through the postpartum 6th week information form that developed by the researchers on the basis of the literature.