South African Gestational Diabetes Mellitus Knowledge Questionnaire

Abstract

The South African Gestational Diabetes Mellitus Knowledge Questionnaire (SA-GDMKQ) is an adapted and linguistically validated psychometric instrument designed to assess condition-specific health literacy, factual understanding, and self-care awareness among pregnant women diagnosed with gestational diabetes mellitus (GDM). Originating from an initial instrument developed in Malaysia by Hussain and colleagues, the scale was systematically adapted, translated, and psychometrically evaluated for use in South Africa’s pluralistic, multilingual public healthcare infrastructure by Manas, Chivese, Coetzee, Conradie, and Morris. The instrument captures a multidimensional construct encompassing foundational disease biology, epidemiological risk factors, nutritional and dietary management, therapeutic medical regimens, and acute and long-term perinatal complications affecting both maternal and fetal dyads.

Structurally, the questionnaire consists of items formatted with multiple-choice alternatives including a dedicated “I do not know” option to mitigate guessing bias. Psychometric evaluations conducted across three official languages of the Western Cape region—English, Afrikaans, and isiXhosa—demonstrated strong content and face validity through multidisciplinary expert panel reviews and qualitative cognitive pre-testing. Internal consistency analyses yielded Cronbach’s alpha coefficients of 0.434 for the English version, 0.534 for the Afrikaans version, and 0.621 for the isiXhosa version. These values reflect the broad, formative breadth inherent to clinical knowledge indexes where domain components do not necessarily co-vary unidimensionally. Test-retest reliability evaluated across a two-week interval exhibited moderate stability in aggregate scores, although individual item-level concordance demonstrated wide variation. The SA-GDMKQ fills a critical void in maternal health psychology in sub-Saharan Africa, enabling clinicians and behavioral researchers to identify specific educational deficits, optimize diabetes self-management education, and evaluate the efficacy of antenatal health interventions.

Keywords

Gestational Diabetes Mellitus, Health Literacy, Psychometrics, Maternal Health Psychology, Cross-Cultural Adaptation, Antenatal Education, Disease Knowledge Questionnaire, Perinatal Outcomes, Self-Management, South Africa

Authors

The cross-cultural adaptation, translation, and initial clinical psychometric validation of the South African Gestational Diabetes Mellitus Knowledge Questionnaire were conducted by an interdisciplinary team of researchers and clinical specialists affiliated with Stellenbosch University in the Western Cape, South Africa:

• Lorisha Manas (Corresponding Author: [email protected]) — Division of Epidemiology and Biostatistics, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
• Tawanda Chivese — Department of Population Health, College of Medicine, QU Health, Qatar University, Doha, Qatar; and Division of Epidemiology and Biostatistics, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
• Ankia Coetzee — Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Cape Town, South Africa.
• Magda Conradie — Division of Endocrinology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Academic Hospital, Cape Town, South Africa.
• Linzette D. Morris (Corresponding Author: [email protected]) — Department of Physical Therapy and Rehabilitation Science, College of Health Sciences, QU Health, Qatar University, Doha, Qatar; and Department of Health and Rehabilitation Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.

Purpose

Gestational diabetes mellitus is characterized by spontaneous hyperglycemia first recognized during pregnancy, posing severe immediate and long-term hazards to both mother and fetus. Clinical sequelae include pre-eclampsia, maternal birth trauma, fetal macrosomia, shoulder dystocia, neonatal respiratory distress, hypoglycemia, and an elevated lifelong risk for both mother and offspring of developing type 2 diabetes mellitus. Managing GDM requires rapid, intensive behavioral adaptation immediately following diagnosis, involving rigorous daily self-monitoring of blood glucose, complex dietary alterations, adherence to physical activity guidelines, and, in many cases, pharmacotherapy such as insulin injections or oral hypoglycemic agents.

Despite these clinical demands, antenatal healthcare services in low- and middle-income countries (LMICs), particularly across Southern Africa, frequently operate under substantial resource limitations. Overburdened public referral clinics, constrained consultation times, systemic inequalities, and widespread disparities in baseline educational attainment create pronounced barriers to effective patient education. Clinicians cannot simply presume that diagnostic disclosures translate into functional patient understanding. Prior to the development and adaptation of the SA-GDMKQ, South African clinicians and clinical researchers lacked a standardized, culturally validated, and linguistically accessible instrument to quantify what pregnant women actually understand about their diagnosis.

The purpose of the SA-GDMKQ is threefold:

• Diagnostic Screening of Educational Needs: To provide primary healthcare nurses, diabetes educators, dietitians, and obstetricians with a rapid, objective metric to evaluate baseline disease-specific health literacy at the point of GDM diagnosis, identifying critical misconceptions and dangerous gaps in knowledge.
• Intervention Customization and Triage: To enable healthcare providers to tailor psychoeducational counseling directly to individual deficits—such as targeting dietary misunderstandings or addressing anxieties surrounding insulin therapy—rather than relying on generic, standardized lectures that may fail to address the patient’s specific informational needs.
• Empirical Research and Program Evaluation: To serve as a standardized dependent variable in clinical trials, behavioral medicine research, and maternal-child health studies evaluating the effectiveness of novel educational interventions, community health worker programs, and digital health initiatives across linguistically heterogeneous populations.

Psychological Construct

The psychological construct assessed by the SA-GDMKQ is condition-specific health literacy, operationalized as the patient’s factual comprehension, procedural awareness, and cognitive appraisal of gestational diabetes mellitus and its therapeutic management. In health psychology and psychometrics, health literacy is recognized as an active cognitive and behavioral resource rather than passive memorization. It forms the cognitive substrate upon which self-efficacy, risk perception, and self-regulatory behaviors are built.

Within the SA-GDMKQ framework, this construct is conceptualized as multidimensional, spanning five interdependent domains of operational knowledge:

1. Basic Pathophysiological and Disease Knowledge

This dimension assesses the patient’s fundamental grasp of GDM as a distinct metabolic aberration triggered by pregnancy-induced hormonal shifts and pancreatic beta-cell decompensation. It investigates whether the patient recognizes what GDM is, that it manifests as elevated circulating blood glucose levels, and how it differs from pre-existing chronic diabetes. Misconceptions in this domain—such as believing GDM is a permanent, non-manageable curse or conversely trivializing it as benign fluid retention—can undermine engagement with clinical care.

2. Etiological Risk Factors and Epidemiology

This subscale evaluates the respondent’s awareness of personal and familial vulnerabilities that elevate susceptibility to GDM. Key indicators include pre-pregnancy maternal obesity, advanced maternal age, prior history of delivering macrosomic infants, and familial patterns of diabetes mellitus. Understanding risk factors helps dispel self-blame, enhances psychological acceptance, and reinforces the biological reality of the condition.

3. Nutritional and Dietary Management

Dietary modification serves as the first-line therapeutic pillar in GDM management. This dimension measures the patient’s operational knowledge regarding macronutrient quality, carbohydrate portion control, glycemic index concepts, the hazards of consuming refined sugars, and the critical importance of consistent meal timing. Crucially, it examines whether patients harbor dangerous misconceptions, such as believing that skipping meals is an effective method to control hyperglycemia, which can paradoxically induce maternal ketoacidosis or reactive hypoglycemia.

4. Therapeutic Interventions, Pharmacotherapy, and Self-Monitoring

This facet examines procedural and technical knowledge regarding disease management protocols. It assesses comprehension of home blood glucose monitoring (HBGM), acceptable target glycemic ranges, physical activity recommendations (such as brisk walking), and indications for pharmacotherapy. A major psychometric focus is measuring attitudes and knowledge concerning insulin, specifically evaluating whether patients hold unwarranted fears that insulin cross-contaminates the placenta or causes congenital fetal deformities.

5. Perinatal Complications and Long-Term Prognosis

The final dimension evaluates the patient’s cognitive appraisal of the health trajectories of both mother and neonate. It measures awareness of intrapartum complications (e.g., severe perineal tearing, emergency cesarean section secondary to macrosomia), acute neonatal hazards (e.g., neonatal hypoglycemia, respiratory distress), and long-term postpartum risks, specifically the elevated lifetime risk of developing chronic type 2 diabetes mellitus. Additionally, it evaluates knowledge regarding protective postpartum behaviors, such as infant breastfeeding and mandatory 6-to-12-week postpartum oral glucose tolerance testing.

Theoretical Framework

The conceptual architecture of the SA-GDMKQ is anchored in several prominent models of health behavior, cognitive psychology, and psychometric measurement:

The Information-Motivation-Behavioral Skills (IMB) Model

Developed by Fisher, Fisher, and colleagues, the Information-Motivation-Behavioral Skills (IMB) model posits that health-related behaviors are a direct function of three interacting components: possessing accurate, actionable information; holding personal and social motivation to act; and mastering specific behavioral skills. Within the IMB paradigm, information is the necessary prerequisite for behavior change. When applied to GDM, accurate knowledge regarding carbohydrate metabolism, insulin function, and fetal vulnerability directly informs a woman’s motivation and equips her to execute the complex behavioral skills needed for glycemic control.

The Health Belief Model (HBM)

The Health Belief Model (Rosenstock, 1974; Becker, 1974) provides a complementary theoretical lens. The HBM asserts that individuals engage in preventative or therapeutic health behaviors if they perceive themselves to be susceptible to a condition (perceived susceptibility), believe the condition carries severe physical or social consequences (perceived severity), and believe that available actions will successfully mitigate these risks (perceived benefits) without being outweighed by psychological, financial, or physical costs (perceived barriers). The SA-GDMKQ directly measures the cognitive foundations of perceived susceptibility and severity by probing maternal awareness of fetal macrosomia, stillbirth, pre-eclampsia, and long-term maternal diabetes. Furthermore, by evaluating knowledge of nutritional regimens and insulin safety, the scale evaluates the patient’s grasp of the perceived benefits of treatment regimens, dismantling perceived barriers rooted in medical misinformation.

Formative vs. Reflective Measurement Models in Cognitive Testing

From a classical psychometric standpoint, knowledge scales diverge fundamentally from personality or affective scales. In reflective measurement models (common in anxiety or depression inventories), the latent construct causes the item responses, leading to high inter-item correlations and high Cronbach’s alphas. In contrast, knowledge questionnaires frequently behave as formative or composite measurement models (Bollen & Lennox, 1991). In a formative construct, individual items define and compose the construct rather than merely reflecting it. A pregnant woman may possess accurate knowledge regarding dietary fiber and carbohydrate restriction while remaining entirely uninformed about postpartum glucose tolerance testing or insulin pharmacodynamics. Thus, domain divergence is theoretically expected and psychometrically defensible.

Validity

The validation of the SA-GDMKQ was executed using a rigorous methodological framework designed to ensure conceptual, semantic, and operational equivalence across diverse cultural and linguistic groups in South Africa.

Cross-Cultural Adaptation and Translation Process

The adaptation process adhered strictly to international guidelines for the cross-cultural adaptation of self-report measures established by Beaton et al. (2000). Because the original instrument had been validated in an urban Malaysian tertiary healthcare environment, direct linguistic translation alone was insufficient; comprehensive cultural contextualization was mandatory.

• Forward Translation: Independent bilingual translators whose primary languages were Afrikaans and isiXhosa translated the English source instrument. The translators included both healthcare professionals aware of clinical concepts and lay translators naive to medical terminology.
• Synthesis and Reconciliation: A multidisciplinary review committee compared the forward translations against the original instrument, resolving linguistic ambiguities, colloquial expressions, and semantic discrepancies.
• Backward Translation: Independent professional translators blinded to the original Malaysian version back-translated the Afrikaans and isiXhosa drafts into English to detect hidden conceptual errors or translation-induced bias.
• Multidisciplinary Expert Panel Review: A panel comprising obstetricians, subspecialist endocrinologists, registered dietitians, diabetes nurse educators, and psychometricians critically reviewed every item. The panel evaluated each question for clinical accuracy against the Society for Endocrinology, Metabolism and Diabetes of South Africa (SEMDSA) guidelines, cultural relevance, and linguistic clarity, establishing high content validity.

Cognitive Debriefing and Face Validity

Face validity was confirmed through cognitive interviewing and debriefing sessions involving pregnant women from the target clinical populations across the three linguistic cohorts (English, Afrikaans, and isiXhosa). Participants completed the draft questionnaire while employing a think-aloud protocol, providing qualitative feedback regarding item readability, question clarity, cultural acceptability, and the emotional resonance of terminology. Items identified as confusing or culturally discordant were modified before the final psychometric field trial.

Construct and Criterion Validity Observations

In the clinical validation study involving 124 pregnant women diagnosed with GDM at a public tertiary academic hospital in Cape Town, the instrument demonstrated robust discriminative capability. Total knowledge scores varied in predictable directions relative to participants’ prior educational exposure, socioeconomic position, and parity. However, the study authors highlighted that because clinical knowledge across distinct disease facets (e.g., diet vs. insulin therapy) exhibits domain specificity, further large-scale multi-center testing is required to confirm structural equation modeling parameters and criterion-related predictive validity against objective glycemic markers such as glycated hemoglobin (HbA1c) and continuous glucose monitoring metrics.

Reliability

Reliability estimation for the SA-GDMKQ encompassed assessments of internal consistency and temporal stability (test-retest reliability), revealing psychometric nuances typical of broad health-literacy assessment instruments.

Internal Consistency

Internal consistency was calculated separately for each language adaptation using Cronbach’s alpha (α):

• English Version: α = 0.434
• Afrikaans Version: α = 0.534
• isiXhosa Version: α = 0.621

In traditional psychometric evaluation, a Cronbach’s alpha coefficient below 0.70 is often interpreted as suboptimal for diagnostic decision-making. However, psychometric theorists (e.g., Streiner, 2003; Tavakol & Dennick, 2011) emphasize that Cronbach’s alpha is heavily dependent on test length, item redundancy, and structural unidimensionality. When an instrument is brief (15 to 20 items) yet samples heterogeneous, non-redundant knowledge domains (e.g., pathophysiology, diet, medication, complications, postpartum screening), low inter-item covariance is an expected mathematical consequence. The isiXhosa version demonstrated the highest internal consistency (α = 0.621), suggesting consistent conceptual cohesion among the isiXhosa-speaking participants recruited from public healthcare clinics.

Temporal Stability (Test-Retest Reliability)

Test-retest reliability was evaluated over a two-week interval among stable participants prior to intensive clinical educational interventions. Concordance at the individual item level was assessed using Cohen’s kappa (κ), while aggregate score stability was examined via linear correlation and intraclass correlation coefficients (ICC):

• Item-Level Concordance: Individual item kappa coefficients exhibited substantial variation, ranging from slight negative agreement (κ = -0.03) to almost perfect agreement (κ = 0.89) across individual items in the English cohort. Similar item-level fluctuations were noted in the Afrikaans and isiXhosa cohorts. Items measuring concrete factual behaviors (such as water intake or glucose testing) exhibited greater stability than items assessing complex medical risks.
• Aggregate Total Score Stability: Despite individual item variation, composite knowledge scores demonstrated statistically significant positive linear correlations between initial testing and two-week retesting, confirming adequate aggregate temporal reliability for group-level research and clinical audit purposes.

Factor Analysis

The structural dimensionality of the SA-GDMKQ was evaluated using exploratory factor analysis (EFA) to determine whether the instrument behaves as a single overarching knowledge metric or resolves into discrete cognitive components.

Factor Structure and Dimensionality

Consistent with its theoretical design, factor analytic investigations demonstrated that the SA-GDMKQ is multidimensional. Principal axis factoring and scree plot inspections revealed multiple distinct factors with eigenvalues exceeding Kaiser’s criterion (λ > 1.0). The extracted factors align closely with the five conceptual domains established during expert panel content validation:

1. Basic Disease Understanding: Factor loadings cluster around items concerning the definition of gestational diabetes and the physiological reality of elevated blood glucose.
2. Risk Factor Recognition: Items evaluating maternal body weight, family history, and asymptomatic presentation group onto an etiological awareness factor.
3. Dietary and Lifestyle Self-Regulation: Items measuring knowledge of refined carbohydrates, nutritional regularity (prohibiting meal skipping), and physical exercise load strongly onto a behavioral management factor.
4. Medical and Pharmacological Management: Factor loadings capture procedural knowledge regarding blood glucose self-monitoring and the safety profile of clinical insulin therapy.
5. Prognostic Complications and Postpartum Care: A distinct factor captures items addressing neonatal macrosomia, maternal pre-eclampsia, neonatal hypoglycemia, postpartum glycemic testing, and lifetime risk of type 2 diabetes.

Because items function dichotomously (correct vs. incorrect) and represent formative, factual domains, classical linear factor analysis can encounter difficulty with attenuated item correlations. Confirmatory factor analyses (CFA) conducted on dichotomous variables using robust weighted least squares estimators (WLSMV) indicate that a five-factor first-order model or a bi-factor model (with a general health literacy factor and specific domain factors) provides the most clinically coherent interpretation of the data.

Instrument / Measurement Tool

The operational specifications of the South African Gestational Diabetes Mellitus Knowledge Questionnaire are detailed below:

• Test Type: Disease-specific health literacy and clinical knowledge questionnaire; self-administered or interviewer-administered clinical assessment tool.
• Target Population: Pregnant adult women (aged 18 years and older) with a confirmed clinical diagnosis of gestational diabetes mellitus, attending antenatal, obstetric, or diabetes clinics.
• Administration Format: Paper-and-pencil questionnaire, digital tablet format, or verbally guided administration by trained healthcare personnel for individuals with low basic literacy.
• Administration Time: Approximately 10 to 15 minutes.
• Language Availability: English, Afrikaans, and isiXhosa.
• Item Count: 20 standardized knowledge items (evaluated clinically across 15 core multiple-choice diagnostic stems with comprehensive sub-facets).
• Response Scale: Multiple-choice format featuring categorical response options (True, False, or three content-specific multiple-choice alternatives) accompanied by a mandatory “I do not know” option to eliminate forced guessing.
• Scoring Instructions:
  • Each item is scored dichotomously: 1 point is awarded for each scientifically correct answer.
  • 0 points are assigned for an incorrect response or when selecting the “I do not know” option.
  • Total scores are calculated by summing all correct items. Scores range from 0 to 20 (or 0 to 15 when utilizing the core abbreviated 15-item scoring protocol).
  • Higher aggregate scores indicate superior condition-specific health literacy and greater understanding of GDM self-management.
• Score Interpretation Guidelines:
  • High Knowledge (≥ 80% correct): Indicates robust comprehension of GDM pathophysiology, lifestyle requirements, and medical safety. Patients are well-prepared for collaborative self-care.
  • Moderate Knowledge (60% – 79% correct): Reflects basic familiarity with GDM, but reveals critical gaps in specific domains (e.g., dietary myths or postpartum screening awareness) requiring targeted reinforcement.
  • Low Knowledge (< 60% correct): Signifies substantial deficits in disease literacy. Immediate, structured educational interventions are recommended to prevent self-management errors and clinical complications.

Permissions & Fee and Test Year

The South African adaptation of the Gestational Diabetes Mellitus Knowledge Questionnaire was published in 2025 in South African Family Practice, following the adaptation of the original instrument developed by Hussain, Yusoff, and Sulaiman (2014, 2015). The tool was developed to support public healthcare access and clinical research in low- and middle-income countries. It is accessible for non-commercial academic, clinical, and epidemiological research. Researchers, clinicians, and health systems wishing to utilize, reproduce, or adapt the English, Afrikaans, or isiXhosa versions are encouraged to contact the principal researchers (Stellenbosch University) for complete implementation guidelines, language-specific translation keys, and scoring manuals. The original authors must be cited in all academic dissertations, clinical audits, and peer-reviewed publications utilizing the scale.

References

The following peer-reviewed literature supports the theoretical, psychometric, and clinical foundations of the SA-GDMKQ:

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Items of the Scale