The impact of patients’ involvement in cooking on their mortality and morbidity: A 19-year follow-up of patients diagnosed with type 2 diabetes mellitus

Figures & data

Figure 1. Patient flow through trial.

Table I. Patient characteristics at diabetes diagnosis according to involvement in cooking.

	Involvement in cooking at diabetes diagnosis (n = 1235)^1
	Infrequent (< once per week) (n = 318)		Frequent (2–7 times per week) (n = 917)
	Females (n = 37)	Males (n = 281)	Females (n = 539)	Males (n = 378)
Sociodemographic
Age, years	79.7 (75.2–85.4)	67.9 (58.3–74.7)	66.9 (57.8–74.7)	61.9 (51.7–69.1)
Living alone^2	25 (67.6)	45 (16.0)	201 (37.4)	99 (26.2)
Rural residence^2	10 (27.8)	39 (14.7)	120 (23.2)	97 (26.6)
Basic school education only^2	34 (94.4)	208 (75.6)	453 (86.6)	251 (69.2)
Biochemical
Diagnostic plasma glucose (mmol/L)	13.0 (10.3–16.1)	13.7 (11.1–17.8)	13.7 (10.7–17.0)	13.7 (10.7–16.8)
Fasting triglyceride (mmol/L)	2.03 (1.59–2.88)	1.90 (1.27–2.66)	1.95 (1.41–2.83)	1.99 (1.39–3.24)
Total cholesterol (mmol/L)	6.0 (5.5–7.0)	6.0 (5.1–6.9)	6.3 (5.6–7.3)	6.2 (5.3–6.9)
Microalbuminuria	14 (46.7)	104 (38.5)	173 (33.7)	150 (40.8)
Proteinuria	3 (10.0)	15 (5.6)	17 (3.3)	22 (6.0)
Clinical
Body mass index (kg/m^2)	26.5 (23.6–29.9)	28.5 (25.9–31.1)	29.2 (25.7–33.6)	29.1 (26.6–31.9)
Hypertension	33 (89.2)	196 (69.8)	425 (78.9)	263 (69.6)
Behavioural
Current smoking^2	6 (16.2)	111 (39.5)	145 (27.1)	166 (43.9)
Functional level
Sedentary physical activity^1	31 (83.8)	67 (24.0)	148 (27.6)	81 (21.5)
Low mobility^2,3	30 (81.1)	123 (43.9)	275 (51.4)	127 (33.7)
Home care^2	21 (77.8)	41 (15.2)	97 (18.0)	32 (8.5)
Co-morbidity index^4
0	19 (51.4)	177 (63.0)	397 (73.7)	270 (71.4)
1	9 (24.3)	51 (18.2)	78 (14.5)	60 (15.9)
2	7 (18.9)	25 (8.9)	43 (8.0)	32 (8.5)
≥ 3	2 (5.4)	28 (10.0)	21 (3.9)	16 (4.2)
Randomization group
Structured personal care	22 (59.5)	158 (56.2)	297 (55.1)	205 (54.2)

Notes: Values are numbers (percentages) or medians (inter-quartile range). ¹Based only on patients who consume warm main meals regularly (<5 times per week). ²Data from questionnaires to patients. ³Low mobility is characterized by not being able to walk up or down the stairs from one floor to another without resting. ⁴Charlson's comorbidity index is calculated on 10 years before time of diabetes diagnosis.

Table II. Mortality and morbidity during 19 years of follow-up according to frequency of involvement in cooking.

	No. of patients without the outcome at diagnosis Infrequent/frequent cooking	No. of patients with outcome during 19 years of follow-up, n (%)		Absolute risk (events per 1000 patient years)		Hazard ratios^1 for infrequent versus frequent involvement in cooking
		Infrequent cooking	Frequent cooking	Infrequent cooking	Frequent cooking	Model 1^2 Adjusted for possible confounders	p-value*	Interaction p-value**	Model 2^3 Further adjusted for possible biochemical mediators	p-value*	Interaction p-value**	n (Model 2)
All-cause mortality:
Men	281/378	225 (80.1)	260 (68.8)	80.8	58.1	1.03 (0.85-1.25)	0.77	0.098	1.06 (0.87-1.28)	0.59	0.32	563
Women	37/539	34 (91.9)	349 (64.8)	147.9	51.3	1.39 (0.90–2.14)	0.14		1.32 (0.79–2.20)	0.30		482
Diabetes-related deaths:
Men	281/378	136 (48.6)	166 (44.0)	48.8	37.1	0.97 (0.75–1.24)	0.79	0.032	0.96 (0.74–1.24)	0.76	0.23	561
Women	37/539	24 (64.9)	218 (40.6)	104.4	32.0	1.86 (1.03–3.35)	0.039		1.45 (0.68–3.08)	0.33		480
Any diabetes-related endpoint:
Men	214/313	141 (65.9)	222 (70.9)	82.4	75.7	0.82 (0.65–1.04)	0.11	0.15	0.82 (0.65–1.04)	0.10	0.30	451
Women	23/457	16 (69.6)	325 (71.1)	150.7	71.0	1.34 (0.69–2.60)	0.38		1.19 (0.56–2.54)	0.66		405
Myocardial infarction:
Men	238/348	80 (33.6)	131 (37.6)	34.4	33.2	0.79 (0.57–1.09)	0.15	0.083	0.78 (0.55–1.10)	0.15	0.13	500
Women	30/509	12 (40.0)	164 (32.2)	68.1	26.1	1.28 (0.64–2.58)	0.49		1.19 (0.56–2.54)	0.66		450
Stroke:
Men	264/360	67 (25.4)	83 (23.1)	27.7	20.6	1.16 (0.82–1.64)	0.39	0.11	1.06 (0.74–1.52)	0.74	0.16	534
Women	30/520	7 (23.3)	108 (20.8)	39.6	17.2	2.47 (1.08–5.65)	0.033		2.38 (1.00–5.67)	0.050		464
Peripheral vascular disease:
Men	278/375	14 (5.0)	25 (6.7)	5.1	5.7	0.97 (0.47–2.04)	0.94	0.57	1.11 (0.50–2.44)	0.80	0.62	558
Women	36/537	2 (4.6)	15 (2.8)	8.8	2.2	2.07 (0.13–33.42)	0.61		3.20 (0.13–76.23)	0.47		480
Microvascular disease:
Men	281/377	32 (11.4)	60 (15.9)	11.9	14.3	0.83 (0.52–1.34)	0.45	0.79	0.75 (0.43–1.31)	0.31	0.88	562
Women	37/537	3 (8.1)	65 (12.1)	14.0	9.9	1.00 (0.15–6.51)	0.99		0.59 (0.05–7.80)	0.69		481

Notes: These multivariate analyses include patients who consume warm meals regularly (> 5 times per week). Infrequent cooking: < once time per week, frequent cooking: 2–7 times per week. ¹The hazard ratio (HR) is calculated in a Cox proportional hazard regression model. The corresponding 95% confidence interval (95% CI) and p-values are determined using a sandwich estimator for the variance to account for clustering of patients within practices. *Tests the effect of involvement in cooking within gender groups. **Tests whether the effect of involvement in cooking is different between gender groups. ²Model 1: these analyses are adjusted for age, randomization group, education, living alone, residence, body mass index, hypertension, smoking habits, leisure-time physical activity, low mobility, home care, and Charlson's co-morbidity index. ³Model 2: these analyses are additionally adjusted for diagnostic plasma glucose, fasting triglyceride, total cholesterol, microalbuminuria, and proteinuria.