As you are a diabetic consuming sweets is always harmful as it increases the blood glucose level. This increase in blood glucose level can affect your vital organs like kidney and heart. So consuming sugar sweets is always harmful for a diabetic. So try to restrict your sweets as much as possible and if you want to have, try having it with high fiber foods like salads or soups so that the effect of sugar is not much. You can also go for alternatives of sugar free sweeteners which do not increase your blood glucose level. Also do light exercise after eating a sweet to reduce its effect on blood glucose level.